The formation of the first spore takes place at the same end of the sterigma, and in the same manner a second follows, then a third, and so on; every one which springs up later pushes its predecessor in the direction of the axis of the sterigma in the same degree in which it grows itself; every successive spore formed from a sterigma remains for a time in a row with one another. Consequently every sterigma bears on its apex a chain of spores, which are so much the older, the farther they stand from the sterigma. The number of the links in a chain of spores reaches in normal specimens to ten or more. All sterigmata spring up at the same time, and keep pace with one another in the formation of the spores. Every spore grows for a time, according to its construction, and at last separates itself from its neighbours. The mass of dismembered spores forms that fine glaucous hue which is mentioned above. The spores, therefore, are articulated in rows, one after the other, from the ends of the sterigmata. The ripe spore, or conidium, is a cell of a round or broadly oval form, filled with a colourless protoplasm, and, if observed separately, is found to be provided with a brownish, finely verruculose, dotted wall.



The same mycelium which forms the pedicel for the conidia when it is near the end of its development, forms by normal vegetation a second kind of fructification. It begins as delicate thin little branches, which are not to be distinguished by the naked eye, and which mostly in four or six turns, after a quickly terminated growth, wind their ends like a corkscrew. (Fig. 102.) The sinuations decrease in width more and more, till they at last reach close to one another, and the whole end changes from the form of a corkscrew into that of a hollow screw. In and on that screw-like body, a change of a complicated kind takes place, which is a productive process. In consequence of this, from the screw body a globose receptacle is formed, consisting of a thin wall of delicate cells, and a closely entwined row of cells surrounded by this dense mass (d). By the enlargement of all these parts the round body grows so much, that by the time it is ripe it is visible to the naked eye. The outer surface of the wall assumes a compactness and a bright yellow colour; the greater part of the cells of the inner mass become asci for the formation of sporidia, while they free themselves from the reciprocal union, take a broad oval form, and each one produces within its inner space eight sporidia (e). These soon entirely fill the ascus. When they are quite ripe, the wall of the conceptacle becomes brittle, and from irregular fissures, arising easily from contact, the colourless round sporidia are liberated.

The pedicels of both kinds of fruit are formed from the same mycelium in the order just described. If we examine attentively, we can often see both springing up close to one another from the same filament of a mycelium. This is not very easy in the close interlacing of the stalks of a mass of fungi in consequence of their delicacy and fragility. Before their connection was known, the conceptacles and the conidia pedicels were considered as organs of two very different species of fungi. The conceptacles were called Eurotium herbariorum, and the conidia bearers were called Aspergillus glaucus.

Allied to Eurotium is the group of Erysiphei, in which well-authenticated polymorphy prevails. These fungi are developed on the green parts of growing plants, and at first consist of a white mouldy stratum, composed of delicate mycelium, on which erect threads are produced, which break up into subglobose joints or conidia. The species on grass was named Oidium monilioides before its relationship was known, but undoubtedly this is only the conidia of Erysiphe graminis. In like manner the vine disease (Oidium Tuckeri) is most probably only the conidia of a species of Erysiphe, of which the perfect condition has not yet been discovered. On roses the old Oidium leucoconium is but the conidia of Sphaerotheca pannosa, and so of other species. The Erysiphe which ultimately appears on the same mycelium consists of globose perithecia, externally furnished with thread-like appendages, and internally with asci containing sporidia. In this genus there are no less than five different forms of fruit,[E] the multiform threads on the mycelium, already alluded to as forms of Oidium, the asci contained in the sporangia, which is the proper fruit of the Erysiphe, larger stylospores which are produced in other sporangia, the smaller stylospores which are generated in the pycnidia, and separate sporules which are sometimes formed in the joints of the necklaces of the conidia. These forms are figured in the "Introduction to Cryptogamic Botany" from Sphaerotheca Castagnei, which is the hop mildew.[F] The vine disease, hop mildew, and rose mildew, are the most destructive species of this group, and the constant annoyance of cultivators.



When first describing an allied fungus found on old paper, and named Ascotricha chartarum, the Rev. M. J. Berkeley called attention to the presence of globose conidia attached to the threads which surround the conceptacles,[G] and this occurred as long since as 1838. In a recent species of Chaetomium found on old sacking, Chaetomium griseum, Cooke,[H] we have found tufts in all respects similar externally to the Chaetomium, but no perithecium was formed, naked conidia being developed apparently at the base of the coloured threads. In Chaetomium funicolum, Cooke, a black mould was also found which may possibly prove to be its conidia, but at present there is no direct evidence.

The brothers Tulasne have made us acquainted with a greater number of instances amongst the Sphaeriacei in which multiple organs of reproduction prevail. Very often old and decaying individuals belonging to species of Boletus will be found filled, and their entire substance internally replaced, by the threads and multitudinous spores of a golden yellow parasite, to which the name of Sepedonium chrysospermum has been given. According to Tulasne, this is merely a condition of a sphaeriaceous fungus belonging to his genus Hypomyces.[I]

The same observers also first demonstrated that Trichoderma viride, P., was but the conidia-bearing stage of Hypocrea rufa, P., another sphaeriaceous fungus. The ascigerous stroma of the latter is indeed frequently associated in a very close manner with the cushions of the pretended Trichoderma, or in other cases the same stroma will give rise to a different apparatus of conidia, of which the principal elements are acicular filaments, which are short, upright, and almost simple, and which give rise to small oval conidia which are solitary on the tips of the threads. Therefore this Hypocrea will possess two different kinds of conidia, as is the case in many species of Hypomyces.

A most familiar instance of dualism will be found in Nectria cinnabarina, of which the conidia form is one of the most common of fungi, forming little reddish nodules on all kinds of dead twigs.[J]



Almost any small currant twig which has been lying on the ground in a damp situation will afford an opportunity of studying this phenomenon. The whole surface of the twig will be covered from end to end with little bright pink prominences, bursting through the bark at regular distances, scarcely a quarter of an inch apart. Towards one end of the twig probably the prominences will be of a deeper, richer colour, like powdered cinnabar. The naked eye is sufficient to detect some difference between the two kinds of pustules, and where the two merge into each other specks of cinnabar will be visible on the pink projections. By removing the bark it will be seen that the pink bodies have a sort of paler stem, which spreads above into a somewhat globose head, covered with a delicate mealy bloom. At the base it penetrates to the inner bark, and from it the threads of mycelium branch in all directions, confined, however, to the bark, and not entering the woody tissues beneath. The head, placed under examination, will be found to consist of delicate parallel threads compacted together to form the stem and head. Some of these threads are simple, others are branched, bearing here and there upon them delicate little bodies, which are readily detached, and which form the mealy bloom which covers the surface. These are the conidia, little slender cylindrical bodies, rounded at the ends.

]

Passing to the other bodies, which are of a deeper colour, it will soon be discovered that, instead of being simple rounded heads, each tubercle is composed of numerous smaller, nearly globose bodies, closely packed together, often compressed, all united to a base closely resembling the base of the other tubercles. If for a moment we look at one of the tubercles near the spot where the crimson tubercles seem to merge into the pink, we shall not only find them particoloured, but that the red points are the identical globose little heads just observed in clusters. This will lead to the suspicion, which can afterwards be verified, that the red heads are really produced on the stem or stroma of the pink tubercles.

A section of one of the red tubercles will show us how much the internal structure differs. The little subglobose bodies which spring from a common stroma or stem are hollow shells or capsules, externally granular, internally filled with a gelatinous nucleus. They are, indeed, the perithecia of a sphaeriaceous fungus of the genus Nectria, and the gelatinous nucleus contains the fructification. Still further examination will show that this fructification consists of cylindrical asci, each enclosing eight elliptical sporidia, closely packed together, and mixed with slender threads called paraphyses.

Here, then, we have undoubted evidence of Nectria cinnabarina, with its fruit, produced in asci growing from the stroma or stem, and in intimate relationship with what was formerly named Tubercularia vulgaris. A fungus with two forms of fruit, one proper to the pink, or Tubercularia form, with naked slender conidia, the other proper to the mature fungus, enclosed in asci, and generated within the walls of a perithecium. Instances of this kind are now known to be far from uncommon, although they cannot always, or often, be so clearly and distinctly traced as in the illustration which we have selected.



It is not uncommon for the conidia of the Sphaeria to partake of the characteristics of a mould, and then the perithecia are developed amongst the conidial threads. A recently recorded instance of this relates to Sphaeria Epochnii, B. and Br.,[L] the conidia form of which was long known before the Sphaeria related to it was discovered, under the name of Epochnium fungorum. The Epochnium forms a thin stratum, which overruns various species of Corticium. The conidia are at first uniseptate. The perithecia of the Sphaeria are at first pale bottle-green, crowded in the centre of the Epochnium, then black green granulated, sometimes depressed at the summit, with a minute pore. The sporidia are strongly constricted in the centre, at first uniseptate, with two nuclei in each division.

Another Sphaeria in which the association is undoubted is the Sphaeria aquila, Fr.,[M] which is almost always found nestling in a woolly brown subiculum, for the most part composed of barren brown jointed threads. These threads, however, produce, under favourable conditions, mostly before the perfection of the perithecia, minute subglobose conidia, and in this state constitute what formerly bore the name of Sporotrichum fuscum, Link., but now recognized as the conidia of Sphaeria aquila.

In Sphaeria nidulans, Schw., a North American species, we have more than once found the dark brown subiculum bearing large triseptate conidia, having all the characters of the genus Helminthosporium. In Sphaeria pilosa, P., Messrs. Berkeley and Broome have observed oblong conidia, rather irregular in outline, terminating the hairs of the perithecium.[N] The same authors have also figured the curious pentagonal conidia springing from flexuous threads accompanying Sphaeria felina, Fckl.,[O] and also the threads resembling those of a Cladotrichum with the angular conidia of Sphaeria cupulifera, B. and Br.[P] A most remarkable example is also given by the Brothers Tulasne in Pleospora polytricha, in which the conidia-bearing threads not only surround, but grow upon the perithecia, and are crowned by fascicles of septate conidia.[Q]

Instances of this kind have now become so numerous that only a few can be cited as examples of the rest. It is not at all improbable that the majority of what are now classed together as species under the genus of black moulds, Helminthosporium, will at some not very distant period be traced as the conidia of different species of ascomycetous fungi. The same fate may also await other allied genera, but until this association is established, they must keep the rank and position which has been assigned to them.

Another form of dualism, differing somewhat in character from the foregoing, finds illustration in the sphaeriaceous genus Melanconis, of Tulasne, in which the free spores are still called conidia, though in most instances produced in a sort of spurious conceptaculum, or borne on short threads from a kind of cushion-shaped stroma. In the Melanconis stilbostoma,[R] there are three forms, one of slender minute bodies, oozing out in the form of yellow tendrils, which may be spermatia, formerly called Nemaspora crocea. Then there are the oval brown or olive brown conidia, which are at first covered, then oozing out in a black pasty mass, formerly Melanconium bicolor, and finally the sporidia in asci of Sphaeria stilbostoma, Fries. In Melanconis Berkeleii, Tul., the conidia are quadrilocular, previously known as Stilbospora macrosperma, B. and Br. In a closely-allied species from North America, Melanconis bicornis, Cooke, the appendiculate sporidia are similar, and the conidia would also appear to partake of the character of Stilbospora. We may remark here that we have seen a brown mould, probably an undescribed species of Dematiei, growing in definite patches around the openings in birch bark caused by the crumpent ostiola of the perithecia of Melanconis stilbostoma, from the United States.

In Melanconis lanciformis,[S] Tul., there are, it would appear, four forms of fruit. One of these consists of conidia, characterized by Corda as Coryneum disciforme.[T] Stylospores, which are also figured by Corda under the name of Coniothecium betulinum; pycnidia,[U] first discovered by Berkeley and Broome, and named by them Hendersonia polycystis;[V] and the ascophorous fruits which constituted the Sphaeria lanciformis of Fries. Mr. Currey indicated Hendersonia polycystis, B. and Br., as a form of fruit of this species in a communication to the Royal Society in 1857.[W] He says this plant grows upon birch, and is in perfection in very moist weather, when it may be recognized by the large black soft gelatinous protuberances on the bark, formed by spores escaping and depositing themselves upon and about the apex of the perithecium. This I suspect to be an abnormal state of a well-known Sphaeria (S. lanciformis), which grows upon birch, and upon birch only.

We might multiply, almost indefinitely, instances amongst the Sphaeriacei, but have already given sufficient for illustration, and will therefore proceed briefly to notice some instances amongst the Discomycetes, which also bear their complete or perfect fruit in asci.

The beautiful purple stipitate cups of Bulgaria sarcoides, which may be seen flourishing in the autumn on old rotten wood, are often accompanied by club-shaped bodies of the same colour; or earlier in the season these clavate bodies may be found alone, and at one time bore the name of Tremella sarcoides. The upper part of these clubs disseminate a great abundance of straight and very slender spermatia. Earlier than this they are covered with globose conidia. The fully-matured Bulgaria develops on its hymenium clavate delicate asci, each enclosing eight elongated hyaline sporidia, so that we have three forms of fruit belonging to the same fungus, viz. conidia and spermatia in the Tremella stage, and sporidia contained in asci in the mature condition.[X] The same phenomena occur with Bulgaria purpurea, a larger species with different fruit, long confounded with Bulgaria sarcoides.

On the dead stems of nettles it is very common to meet with small orange tubercles, not much larger than a pin's head, which yield at this stage a profusion of slender linear bodies, produced on delicate branched threads, and at one time bore the name of Dacrymyces Urticae, but which are now acknowledged to be only a condition of a little tremelloid Peziza of the same size and colour, which might be mistaken for it, if not examined with the microscope, but in which there are distinct asci and sporidia. Both forms together are now regarded as the same fungus, under the name of Peziza fusarioides, B.

The other series of phenomena grouped together under the name of polymorphism relate to forms which are removed from each other, so that the mycelium is not identical, or, more usually, produced on different plants. The first instance of this kind to which we shall make reference is one of particular interest, as illustrative of the old popular creed, that berberry bushes near corn-fields produced mildewed corn. There is a village in Norfolk, not far from Great Yarmouth, called "Mildew Rollesby," because of its unenviable notoriety in days past for mildewed corn, produced, it was said, by the berberry bushes, which were cut down, and then mildew disappeared from the corn-fields, so that Rollesby no longer merited its sobriquet. It has already been shown that the corn-mildew (Puccinia graminis) is dimorphous, having a one-celled fruit (Trichobasis), as well as a two-celled fruit (Puccinia). The fungus which attacks the berberry is a species of cluster-cup (AEcidium berberidis), in which little cup-like peridia, containing bright orange pseudospores, are produced in tufts or clusters on the green leaves, together with their spermogonia.

De Bary's observations on this association of forms were published in 1865.[Y] In view of the popular belief, he determined to sow the spores of Puccinia graminis on the leaves of the berberry. For this purpose he selected the septate resting spores from Poa pratensis and Triticum repens. Having caused the spores to germinate in a moist atmosphere, he placed fragments of the leaves on which they had developed their secondary spores on young but full-grown berberry leaves, under the same atmospheric conditions. In from twenty-four to forty-eight hours a quantity of the germinating threads had bored through the walls and penetrated amongst the subjacent cells. This took place both on the upper and under surface of the leaves. Since, in former experiments, it appeared that the spores would penetrate only in those cases where the plant was adapted to develop the parasite, the connection between P. graminis and AEcid. berberidis seemed more than ever probable. In about ten days the spermogonia appeared. After a time the cut leaves began to decay, so that the fungus never got beyond the spermogonoid stage. Some three-year-old seedlings were then taken, and the germinating resting spores applied as before. The plants were kept under a bell-glass from twenty-four to forty-eight hours, and then exposed to the air like other plants. From the sixth to the tenth day, yellow spots appeared, with single spermogonia; from the ninth to the twelfth, spermogonia appeared in numbers on either surface; and, a few days later, on the under surface of the leaves, the cylindrical sporangia of the AEcidium made their appearance, exactly as in the normally developed parasite, except that they were longer, from being protected from external agents. The younger the leaves, the more rapid was the development of the parasite, and sometimes, in the younger leaves, the luxuriance was far greater than in free nature. Similar plants, to the number of two hundred, were observed in the nursery, and though some of them had AEcidium pustules, not one fresh pustule was produced; while two placed under similar circumstances, but without the application of any resting spores, remained all the summer free from AEcidium. It seems, then, indubitable so far that AEcidium berberidis does spring from the spores of Puccinia graminis.

It has, however, to be remarked that De Bary was not equally successful in producing the Puccinia from the spores of the AEcidium. In many cases the spores do not germinate when placed on glass, and they do not preserve their power of germinating very long. He reverts then to the evidence of experiments instituted by agriculturists. Boenninghausen remarked, in 1818, that wheat, rye, and barley which were sown in the neighbourhood of a berberry bush covered with AEcidium contracted rust immediately after the maturation of the spores of the AEcidia. The rust was most abundant where the wind carried the spores. The following year the same observations were repeated; the spores of the AEcidium were collected, and applied to some healthy plants of rye. After five or six days these plants were affected with rust, while the remainder of the crop was sound. In 1863 some winter rye was sown round a berberry bush, which in the following year was infested with AEcidium, which was mature in the middle of May, when the rye was completely covered with rust. Of the wild grasses near the bush, Triticum repens was most affected. The distant plants of rye were free from rust.



The spores of the AEcidium would not germinate on berberry leaves; the berberry AEcidium could not therefore spring from the previous AEcidium. The uredospores of Puccinia graminis on germinating penetrate into the parenchym of the grass on which they are sown; but on berberry leaves, if the tips of the threads enter for a short distance into the stomates their growth at once ceases, and the leaves remain free from parasites.



Montagne has, however, described a Puccinia berberidis on leaves of Berberis glauca from Chili, which grows in company with AEcidium berberidis. This at first sight seems to contradict the above conclusions; but the AEcidium which from the same disc produces the puccinoid resting spores, appears to be different from the European species, inasmuch as the cells of the wall of the sporangium are twice as large, and the spores decidedly of greater diameter.[Z] The resting spores, moreover, differ not only from those of Puccinia graminis, but from those of all other European species.

From this account, then, it is extremely probable that the AEcidium of the berberry enters into the cycle of existence of Puccinia graminis, and, if this be true, wherefore should not other species of Puccinia be related in like manner to other AEcidia? This is the conclusion to which many have arrived, and, taking advantage of certain presumptions, have, we fear, rashly associated many such forms together without substantial evidence. On the leaves of the primrose we have commonly a species of AEcidium, Puccinia, and Uromyces nearly at the same time; we may imagine that all these belong to one cycle, but it has not yet been proved. Again, Uromyces cacaliae, Unger, Uredo cacaliae, Unger, and AEcidium cacaliae, Thumen, are considered by Heufler[a] to form one cycle. Numerous others are given by Fuckel,[b] and De Bary, in the same memoir from which we have already cited, notes Uromyces appendiculatus, Link., U. phaseolorum, Tul., and Puccinia tragopogonis, Ca., as possessing five kinds of reproductive organs. Towards the end of the year, shortly stipitate spores appear on their stroma, which do not fall off. These spores, which do not germinate till after a shorter or longer winter rest, may conveniently be called resting spores, or, as De Bary calls them, teleutospores, being the last which are produced. These at length germinate, become articulated, and produce ovate or kidney-shaped spores, which in their turn germinate, penetrating the cuticle of the mother plant, avoiding the stomates or apertures by which it breathes. After about two or three weeks, the mycelium, which has ramified among the tissues, produces an AEcidium, with its constant companion, spermogonia—distinct cysts, that is, from which a quantity of minute bodies ooze out, often in the form of a tendril, the function of which is imperfectly known at present, but which from analogy we regard as a form of fruit, though it is just possible that they may be rather of the nature of spermatozoids. The AEcidia contain, within a cellular membranous sac, a fructifying disc, which produces necklaces of spores, which ultimately separate from each other in the form of a granular powder. The grains of which it is composed germinate in their turn, no longer avoiding the stomates as before, but penetrating through their aperture into the parenchym. The new resultant mycelium reproduces the Uredo, or fifth form of fructification, and the Uredo spores fall off like those of the AEcidium, and in respect of germination, and mode of penetration, present precisely the same phenomena. The disc which has produced the Uredo spores now gives rise to the resting spores, and so the cycle is complete.[c]

The late Professor Oersted, of Copenhagen, was of opinion that he had demonstrated the polymorphy of the Tremelloid Uredines, and satisfied himself that the one condition known as Podisoma was but another stage of Roestelia.[d] Some freshly gathered specimens of Gymnosporangium were damped with water, and during the night following the spores germinated profusely, so that the teleutospores formed an orange-coloured powder. A little of this powder was placed on the leaves of five small sorbs, which were damped and placed under bell-glasses. In five days yellow spots were seen on the leaves, and in two days more indications of spermogonia. The spermatia were discharged, and in two months from the first sowing, the peridia of Roestelia appeared, and were developed. "This trial of spores," says Oersted, "has conduced to the result expected, and proves that the teleutospores of Gymnosporangium, when transported upon the sorb, give rise to a totally different fungus, the Roestelia cornuta, that is to say, that an alternate generation comes between these fungi. They appertain in consequence to a single species, and the Gymnosporangium ceased to be an independent species, and must be considered as synonymous with the first generation of Roestelia. The spores have been transported upon young shoots of the juniper-tree, and have now commenced to produce some mycelium in the bark. There is no doubt that in next spring it will result in Gymnosporangium."

Subsequently the same learned professor instituted similar experiments upon other hosts, with the spores of Podisoma, and from thence he concluded that Roestelia and Podisoma, in all their known species, were but forms the one of the other. Hitherto we are not aware that these results have been confirmed, or that the sowing of the spores of Roestelia on juniper resulted in Podisoma. Such experiments should be received always with care, and not too hastily accepted in their apparent results as proven facts. Who shall say that Roestelia would not have appeared on Sorbus within two months without the sowing of Podisoma spores?—because it is not by any means uncommon for that fungus to appear upon that plant. It is true many mycologists write and speak of Roestelia and Podisoma (or Gymnosporangium) as identical; but, as we think, without the evidence being so complete as to be beyond suspicion. It is, nevertheless, a curious fact that in Europe the number of species of Roestelia and Podisoma are equal, if one species be excluded, which is certainly not a good Podisoma, for the reception of which a new genus has been proposed.[e]

Amongst the ascigerous fungi will be found a curious but interesting genus formerly called Cordyceps, but for which Tulasne, in consequence of the discovery of secondary forms of fruit, has substituted that of Torrubia.[f] These curious fungi partake more or less of a clavate form, and are parasitic on insects. The pupae of moths are sometimes seen bearing upon them the white branched mould, something like a Clavaria in appearance, to which the name of Isaria farinosa has been given. According to Tulasne, this is the conidia form of the bright scarlet, club-shaped body which is also found on dead pupae, called Torrubia militaris. An American mould of the same genus, Isaria sphingum, found on mature moths,[g] is in like manner declared to be the conidia of Torrubia sphingum; whereas a similar mould, found on dead spiders, called Isaria arachnophila,[h] is probably of a similar nature. An allied kind of compact mould, which is parasitic on Cocci, on the bark of trees, recently found in England by Mr. C. E. Broome, and named Microcera coccophila,[i] is said by Tulasne to be a condition of Sphaerostilbe, and it is intimated that other productions of a similar character bear like relations to other sphaeriaceous fungi. For many species of Torrubia no corresponding conidia are yet known.

Some instances might be noted, not without interest, in which the facts of dimorphism or polymorphism have not been satisfactorily proved, but final judgment is held in suspense until suspicion is replaced by conviction. Some years since, a quantity of dead box leaves were collected, on which flourished at the time a mould named Penicillium roseum. This mould has a roseate tint, and occurs in patches on the dead leaves lying upon the ground; the threads are erect and branched above, bearing chains of oblong, somewhat spindle-shaped spores, or, perhaps more accurately, conidia. When collected, these leaves were examined, and nothing was observed or noted upon them except this Penicillium. After some time, certainly between two and three years, during which period the box remained undisturbed, circumstances led to the examination again of one or two of the leaves, and afterwards of the greater number of them, when the patches of Penicillium were found to be intermixed with another mould of a higher development, and far different character. This mould, or rather Mucor, consists of erect branching threads, many of the branches terminating in a delicate globose, glassy head, or sporangium, containing numerous very minute subglobose sporidia. This species was named Mucor hyalinus.[j] The habit is very much like that of the Penicillium, but without any roseate tint. It is almost certain that the Mucor could not have been present when the Penicillium was examined, and the leaves on which it had grown were enclosed in the tin box, but that the Mucor afterwards appeared on the same leaves, sometimes from the same patches, and, as it would appear, from the same mycelium. The great difference in the two species lies in the fructification. In the Penicillium, the spores are naked, and in moniliform threads; whilst in Mucor the spores are enclosed within globose membraneous heads or sporangia. Scarcely can we doubt that the Mucor alluded to above, found thus intermixed, under peculiar circumstances, with Penicillium roseum, is no other than the higher and more complete form of that species, and that the Penicillium is only its conidiiferous state. The presumption in this case is strong, and not so open to suspicion as it would be did not analogy render it so extremely probable that such is the case, apart from the fact of both forms springing from the same mass of mycelium. In such minute and delicate structures it is very difficult to manipulate the specimens so as to arrive at positive evidence. If a filament of mycelium could be isolated successfully, and a fertile thread, bearing the fruit of each form, could be traced from the same individual mycelium thread, the evidence would be conclusive. In default of such conclusive evidence, we are compelled to rest with assumption until further researches enable us to record the assumption as fact.[k]

Apropos of this very connection of Penicillium with Mucor, a similar suspicion attaches to an instance noted by a wholly disinterested observer to this effect. "On a preparation preserved in a moist chamber, on the third day a white speck was seen on the surface, consisting of innumerable 'yeast' cells, with some filaments, branching in all directions. On the fourth day tufts of Penicillium, had developed two varieties—P. glaucum and P. viride. This continued until the ninth day, when a few of the filaments springing up in the midst of the Penicillium were tipped with a dewdrop-like dilatation, excessively delicate—a mere distended pellicle. In some cases they seemed to be derived from the same filament as others bearing the ordinary branching spores of Penicillium, but of this I could not be positive. This kind of fructification increased rapidly, and on the fourteenth day spores had undoubtedly developed within the pellicle, just as had been observed in a previous cultivation, precisely similar revolving movements being also manifested."[l] Although we have here another instance of Mucor and Penicillium growing in contact, the evidence is insufficient to warrant more than a suspicion of their identity, inasmuch as the equally minute spores of Mucor and Penicillium might have mingled, and each producing its kind, no relationship whatever have existed between them, except their development from the same matrix.

Another case of association—for the evidence does not proceed further—was recorded by us, in which a dark-coloured species of Penicillium was closely associated with what we now believe to be a species of Macrosporium—but then designated a Sporidesmium—and a minute Sphaeria growing in succession on damp wall-paper. Association is all that the facts warrant us in calling it.

We cannot forbear alluding to one of the species of Sphaeria to which Tulasne[m] attributes a variety of forms of fruit, and we do so here because we think that a circumstance so extraordinary should be confirmed before it is accepted as absolutely true. This refers to the common Sphaeria found on herbaceous plants, known as Sphaeria (Pleospora) herbarum. First of all the very common mould called Cladosporium herbarum is constituted as conidia, and of this again Macrosporium sarcinula, Berk., is considered to be another condition. In the next place, Cytispora orbicularis, Berk., and Phoma herbarum, West., are regarded as pycnidia, enclosing stylospores. Then Alternaria tenuis, Pr.,[n] which is said to be parasitic on Cladosporium herbarum, is held to be only a form of that species, so that here we have (including the perithecia) no less than six forms or phases for the same fungus. As Macrosporium Cheiranthi, Pr., often is found in company with Cladosporium herbarum, that is also open to suspicion.

We have adduced in the foregoing pages a few instances which will serve to illustrate the polymorphism of fungi. Some of these it will be observed are accepted as beyond doubt, occurring as they do in intimate relationship with each other. Others are considered as scarcely so well established, but probable, although developed sometimes on different species of plants. Finally, some are regarded as hitherto not satisfactorily proved, or, it may be, only suspicious. In this latter group, however much probability may be in their favour, it can hardly be deemed philosophical to accept them on such slender evidence as in some cases alone is afforded. It would not have been difficult to have extended the latter group considerably by the addition of instances enumerated by various mycologists in their works without any explanation of the data upon which their conclusions have been founded. In fact, altogether this chapter must be accepted as illustrative and suggestive, but by no means as exhaustive.

[A] De Bary, in "Quarterly German Magazine" (1872), p. 197.

[B] The method pursued by Messrs. Berkeley and Hoffmann of surrounding the drop of fluid, in which a definite number of spores or yeast globules had been placed, with a pellicle of air, into which the germinating threads might pass and fructify, is perhaps the most satisfactory that has been adopted, though it requires nice manipulation. If carefully managed, the result is irrefragable, though doubts have been cast, without any reason, on their observations.

[C] De Bary, "Uber die Brandpilze" (Berlin, 1853), pl. iv. figs. 3, 4, 5.

[D] A. de Bary, on Mildew and Fermentation, in "Quarterly German Magazine," vol. ii. 1872.

[E] Berkeley, "Introd. Crypt. Bot." p. 78, fig. 20.

[F] See also Berkeley, in "Trans. Hort. Soc. London," vol. ix. p. 68.

[G] Berkeley, in "Ann. Nat. Hist." (June, 1838), No. 116.

[H] "Grevillea," vol. i. p. 176.

[I] Tulasne, "On Certain Fungicolous Sphaeriae," in "Ann. des Sci. Nat." 4^me ser. xiii. (1860), p. 5.

[J] "A Currant Twig, and Something on it," in "Gardener's Chronicle," January 28, 1871.

[K] Figs. 104 to 106 by permission from the "Gardener's Chronicle."

[L] Berkeley and Broome, in "Annals of Natural History" (1866), No. 1177, pl. v. fig. 36; Cooke, "Handbook," ii. p. 866.

[M] Cooke, "Handbook," ii. p. 853, No. 2549; specimens in Cooke's "Fungi Britannici Exsiccati," No. 270.

[N] Berk. and Br. "Ann. Nat. Hist." (1865), No. 1096.

[O] "Ann. Nat. Hist." (1871), No. 1332, pl. xx. fig. 23.

[P] Ibid. No. 1333, pl. xxi. fig. 24.

[Q] Tulasne, "Selecta Fungorum Carpologia," ii. p. 269, pl. 29.

[R] Cooke, "Handbook," ii. p. 878; Tulasne, "Carpologia," ii. p. 120, plate 14.

[S] Tulasne, "Selecta Fung. Carp.," ii. plate 16.

[T] Corda, "Icones Fungorum," vol. iii. fig. 91.

[U] Corda, "Icones," vol. i. fig. 25.

[V] Berk. and Br. "Ann. Nat. Hist." No. 415.

[W] Currey, in "Philosoph. Trans. Roy. Soc." (1857), pl. 25.

[X] Tulasne, "On the Reproductive Apparatus of Fungi," in "Comptes Rendus" (1852), p. 841; and Tulasne, "Selecta Fungorum Carpologia," vol. iii.

[Y] "Monatsbericht der Koniglichen Preuss, Acad. der Wissenschaften au Berlin," Jan. 1865; Summary, in "Journ. Roy. Hort. Soc., London," vol. i. n.s. p. 107.

[Z] We have before us an AEcidium on leaves of Berberis vulgaris, collected at Berne by Shuttleworth in 1833. It is named by him AEcidium graveolens, and differs in the following particulars from AEcidium berberidis. The peridia are scattered as in AE. Epilobii, and not collected in clusters. They are not so much elongated. The cells are larger, and the orange spores nearly twice the diameter. There is a decided, strong, but unpleasant odour in the fresh plant; hence the name. The above figures (figs. 107, 108) of the cells and spores of both species are drawn by camera lucida to the same scale—380 diameters.

[a] Freiherrn von Hohenbuehel-Heufler, in "Oesterr. Botan. Zeitschrift," No. 3, 1870.

[b] Fuckel, "Symbolae Mycologicae" (1869), p. 49.

[c] Almost simultaneously with De Bary, the late Professor Oersted instituted experiments, from which the same results ensued, as to AEcidium berberidis and Puccinia graminis. See "Journ. Hort. Soc. Lond." new ser. i., p. 85.

[d] "Oversigt over det Kon. Danske Videns. Selskabs" (1866), p. 185, t. 3, 4; (1867,) p. 208, t. 3, 4; "Resume du Bulletin de la Soc. Roy. Danoise des Sciences" (1866), p. 15; (1867), p. 38; "Botanische Zeitung" (1867), p. 104; "Quekett Microscopical Club Journal," vol. ii. p. 260.

[e] This is Podisoma foliicola, B. and Br., or, as proposed in "Journ. Quekett Club," ii. p. 267, Sarcostroma Berkeleyi, C.

[f] Tulasne, "Selecta Fungorum Carpologia," iii. p. 6, pl. i. figs. 19-31.

[g] Cramer's "Papilio Exotic" (1782), fig. 267.

[h] Cooke, "Handbook," p. 548, No. 1639.

[i] Ibid. p. 556, No. 1666.

[j] Specimens were published under this name in Cooke's "Fungi Britannici Exsiccati," No. 359.

[k] Cooke, "On Polymorphism in Fungi," in "Popular Science Review."

[l] Lewis's "Report on Microscopic Objects found in Cholera Evacuations," Calcutta, 1870.

[m] Tulasne, "Selecta Fungorum Carpologia," ii. p. 261.

[n] Corda, "Prachtflora," plate vii.



X.

INFLUENCES AND EFFECTS.

It is no longer doubted that fungi exercise a large and very important influence in the economy of nature. It may be that in some directions these influences are exaggerated; but it is certain that on the whole their influence is far more important for evil and for good than that of any other of the Cryptogamia. In our endeavour to estimate the character and extent of these influences it will prove advantageous to examine them under three sections. 1. Their influence on man. 2. Their influence on lower animals. 3. Their influence on vegetation. Under these sections the chief facts may be grouped, and some approximate idea obtained of the very great importance of this family of inferior plants, and consequently the advisability of pursuing their study more thoroughly and nationally than has hitherto been done.

I. In estimating the influence of fungi upon man, we naturally enough seek in the first instance to know what baneful effects they are capable of producing on food. Although in the case of "poisonous fungi," popularly understood, fungi may be the passive agents, yet they cannot be ignored in an inquiry of this nature. Writing of the Uses of Fungi, we have already shown that a large number are available for food, and some of these real delicacies; so, on the other hand, it becomes imperative, even with stronger emphasis, to declare that many are poisonous, and some of them virulently so. It is not sufficient to say that they are perfectly harmless until voluntarily introduced into the human system, whilst it is well known that accidents are always possible, and probably would be if every baneful fungus had the word POISON inscribed in capitals on its pileus.

The inquiry is constantly being made as to what plain rules can be given for distinguishing poisonous from edible fungi, and we can answer only that there are none other than those which apply to flowering plants. How can aconite, henbane, oenanthe, stramonium, and such plants, be distinguished from parsley, sorrel, watercress, or spinach? Manifestly not by any general characters, but by specific differences. And so it is with the fungi. We must learn to discriminate Agaricus muscarius from Agaricus rubescens, in the same manner as we would discriminate parsley from AEthusa cynapium. Indeed, fungi have an advantage in this respect, since one or two general cautions can be given, when none such are applicable for higher plants. For instance, it may be said truly that all fungi that exhibit a rapid change to blue when bruised or broken should be avoided; that all Agarics are open to suspicion which possess an acrid taste; that fungi found growing on wood should not be eaten unless the species is well known; that no species of edible fungus has a strong, unpleasant odour, and similar cautions, which, after all, are insufficient. The only safe guide lies in mastering, one by one, the specific distinctions, and increasing the number of one's own esculents gradually, by dint of knowledge and experience, even as a child learns to distinguish a filbert from an acorn, or with wider experience will thrust in his mouth a leaf of Oxalis and reject that of the white clover.

One of the most deleterious of fungi that we possess is at the same time one of the most beautiful. This is the Agaricus muscarius, or Fly Agaric, which is sometimes used as a fly poison.[A] It has a bright crimson pileus studded with pale whitish (sometimes yellowish) warts, and a stem and gills of ivory whiteness. Many instances have been recorded of poisoning by this fungus, and amongst them some British soldiers abroad, and yet it cannot be doubted that this fungus is eaten in Russia. Two instances have come under our notice of persons with some botanical knowledge, and one a gardener, who had resided in Russia and eaten of this fungus. In one case the Fly Agaric was collected and shown to us, and in the other the figure was indicated, so that we might be under no doubt as to the species. Only one hypothesis can be advanced in explanation. It is known that a large number of fungi are eaten in Russia, and that they enter much into the domestic cookery of the peasantry, but it is also known that they pay considerable attention to the mode of cooking, and add a large amount of salt and vinegar, both of which, with long boiling, must be powerful agents in counteracting the poison (probably somewhat volatile) of such fungi as the Fly Agaric. In this place we may give a recipe published by a French author of a process for rendering poisonous fungi edible. It must be taken on his authority, and not our own, as we have never made the experiment, notwithstanding it seems somewhat feasible:—For each pound of mushrooms, cut into moderately small pieces, take a quart of water acidulated with two or three spoonfuls of vinegar, or two spoonfuls of bay salt. Leave the mushrooms to macerate in the liquid for two hours, then wash them with plenty of water; this done, put them in cold water and make them boil. After a quarter or half hour's boiling take them off and wash them, then drain, and prepare them either as a special dish, or use them for seasoning in the same manner as other species.[B]

This method is said to have been tried successfully with some of the most dangerous kinds. Of these may be mentioned the emetic mushroom, Russula emetica, with a bright red pileus and white gills, which has a clear, waxy, tempting appearance, but which is so virulent that a small portion is sufficient to produce disagreeable consequences. It would be safer to eschew all fungi with a red or crimson pileus than to run the risk of indulging in this. A white species, which, however, is not very common, with a bulbous base enclosed in a volva, called Agaricus vernus, should also be avoided. The pink spored species should also be regarded with suspicion. Of the Boleti several turn blue when cut or broken, and these again require to be discarded. This is especially the case with Boletus luridus[C] and Boletus Satanas,[D] two species which have the under surface or orifice of the pores of a vermilion or blood-red colour.

Not only are species which are known to be poisonous to be avoided, but discretion should be used in eating recognized good species. Fungi undergo chemical changes so rapidly that even the cultivated mushroom may cause inconvenience if kept so long after being gathered as to undergo chemical change. It is not enough that they should be of a good kind, but also fresh. The employment of plenty of salt in their preparation is calculated very much to neutralize any deleterious property. Salt, pepper, and vinegar are much more freely employed abroad in preparing fungi than with us, and with manifest advantage.

It is undoubtedly true that fungi exert an important influence in skin diseases. This seems to be admitted on all hands by medical men,[E] however much they may differ on the question of the extent to which they are the cause or consequence of disease. Facts generally seem to bear out the opinion that a great number of skin diseases are aggravated, and even produced, by fungi. Robin[F] insists that a peculiar soil is necessary, and Dr. Fox says it is usually taught that tuberculous, scrofulous, and dirty people furnish the best nidus. It is scarcely necessary to enumerate all these diseases, with which medical men are familiar, but simply to indicate a few. There is favus or scall-head, called also "porrigo," which has its primary seat in the hair follicles. Plica polonica, which is endemic in Russia, is almost cosmopolitan. Then there is Tinea tonsurans, Alopecia, Sycosis, &c., and in India a more deeply-seated disease, the Madura Foot, has been traced to the ravages of a fungus described under the name of Chionyphe Carteri.[G] It is probable that the application of different names to the very often imperfect forms of fungi which are associated with different diseases is not scientifically tenable. Perhaps one or two common moulds, such as Aspergillus or Penicillium, lie at the base of the majority, but this is of little importance here, and does not affect the general principle that some skin diseases are due to fungi.

Whilst admitting that there are such diseases, it must be understood that diseases have been attributed to fungi as a primary cause, when the evidence does not warrant such a conclusion. Diphtheria and thrush have been referred to the devastations of fungi, whereas diphtheria certainly may and does occur without any trace of fungi. Fevers may sometimes be accompanied by fungoid bodies in the evacuations, but it is very difficult to determine them. The whole question of epidemic diseases being caused by the presence of fungi seems based on most incomplete evidence. Dr. Salisbury was of opinion that camp measles was produced by Puccinia graminis, the pseudospores of which germinated in the damp straw, disseminated the resultant secondary bodies in the air, and caused the disease. This has never been verified. Measles, too, has been attributed freely, as well as scarlatina,[H] to fungal influences, and the endeavours to implicate fungi in being the cause of cholera have been pertinaciously persevered in with no conviction. The presence of certain cysts, said to be those of Urocystis, derived from rice, was announced by Dr. Hallier, but when it was shown that no such fungus was found on rice, this phase of the theory collapsed. Special and competent experts were sent from this country to examine the preparations and hear the explanations of Dr. Hallier on his theory of cholera contagion, but they were neither convinced nor satisfied.

As long ago as 1853, Dr. Lauder Lindsay examined and reported on cholera evacuations, and in 1856 he declared—"It will be evident that I can see no satisfactory groundwork for the fungus theory of cholera, which I am not a little surprised to find still possesses powerful advocates."[I] And of the examinations undertaken by him he writes:—"The mycelium and sporules of various species of fungi, constituting various forms of vegetable mould, were found in the scum of the vomit, as well as of the stools, but only at some stage of decomposition. They are found, however, under similar circumstances, in the vomit and stools of other diseases, and, indeed, in all decomposing animal fluids, and they are therefore far from peculiar to cholera."

Some writers have held that the atmosphere is often highly charged with fungi spores, others have denied the presence of organic bodies to any extent in the air. The experiments conducted in India by Dr. Cunningham[J] have been convincing enough on this point. This report states that spores and similar cells were of constant occurrence, and were generally present in considerable numbers. That the majority of the cells were living and ready to undergo development on meeting with suitable conditions was very manifest, as in those cases in which preparations were retained under observation for any length of time, germination rapidly took place in many of the cells; indeed, many spores already germinating were deposited on the slides. In few instances did any development take place beyond the formation of mycelium or masses of toruloid cells, but in one or two distinct sporules were developed on the filaments arising from some of the larger septate spores, and in a few others Penicillium and Aspergillus produced their characteristic heads of fructification.

With regard to the precise nature of the spores and other cells present in various instances little can be said, as, unless their development were to be carefully followed out through all its stages, it is impossible to refer them to their correct species or even genera. The greater number of them are apparently referable to the old orders of fungi—Sphaeronemei, Melanconei, Torulacei, Dematiei, and Mucedines, while some probably belonged to the Pucciniei and Coaemacei. Amongst those belonging to the Torulacei, the most interesting was a representative of the rare genus Tetraploa. Distinct green algoid cells occurred in some specimens. Then follow in the report details of observations made on the rise and fall of diseases, of which diarrhoea, dysentery, cholera, ague, and dengue were selected and compared with the increase or diminution of atmospheric cells. The conclusions arrived at are:—

"Spores and other vegetable cells are constantly present in atmospheric dust, and usually occur in considerable numbers; the majority of them are living, and capable of growth and development. The amount of them present in the air appears to be independent of conditions of velocity and direction of the wind, and their number is not diminished by moisture.

"No connection can be traced between the numbers of bacteria, spores, &c., present in the air, and the occurrence of diarrhoea, dysentery, cholera, ague, or dengue, nor between the presence or abundance of any special form or forms of cells, and the prevalence of any of these diseases.

"The amount of inorganic and amorphous particles and other debris suspended in the atmosphere is directly dependent on conditions of moisture and velocity of wind."

This report is accompanied by fourteen large and well-executed plates, each containing hundreds of figures of organic bodies collected from the air between February and September. It is valuable both for its evidence as to the number and character of the spores in the air, and also for the tables showing the relation between five forms of disease, and their fluctuations, as compared with the amount of spores floating in the atmosphere.

We are fain to believe that we have represented the influence of fungi on man as far as evidence seems to warrant. The presence of forms of mould in some of their incipient conditions in different diseased parts of the human body, externally and internally, may be admitted without the assumption that they are in any manner the cause of the diseased tissues, except in such cases as we have indicated. Hospital gangrene may be alluded to in this connection, and it is possible that it may be due to some fungus allied to the crimson spots (blood rain) which occur on decayed vegetation and meat in an incipient stage of decomposition. This fungus was at one time regarded as an algal, at another as animal; but it is much more probable that it is a low condition of some common mould. The readiness with which the spores of fungi floating in the atmosphere adhere to and establish themselves on all putrid or corrupt substances is manifest in the experience of all who have had to do with the dressing of wounds, and in this case it is a matter of the greatest importance that, as much as possible, atmospherical contact should be avoided.

Recently a case occurred at the Botanic Gardens at Edinburgh which was somewhat novel. The assistant to the botanical professor was preparing for demonstration some dried specimens of a large puff-ball, filled with the dust-like spores, which he accidentally inhaled, and was for some time confined to his room under medical attendance from the irritation they caused. This would seem to prove that the spores of some fungi are liable, when inhaled in large quantities, to derange the system and become dangerous; but under usual and natural conditions such spores are not likely to be present in the atmosphere in sufficient quantity to cause inconvenience. In the autumn a very large number of basidiospores must be present in the atmosphere of woods, and yet there is no reason to believe that it is more unhealthy to breathe the atmosphere of a wood in September or October than in January or May. Dreadful effects are said to be produced by a species of black rust which attacks the large South of Europe reed, Arundo donax. This is in all probability the same species with that which attacks Arundo phragmitis in this country, the spores of which produce violent headaches and other disorders amongst the labourers who cut the reeds for thatching. M. Michel states that the spores from the parasite on Arundo donax, either inhaled or injected, produce violent papular eruption on the face, attended with great swelling, and a variety of alarming symptoms which it is unnecessary to particularize, in various parts of the body.[K] Perhaps if Sarcina should ultimately prove to be a fungus, it may be added to the list of those which aggravate, if they are not the primary cause of, disease in the human subject.

II. What influences can be attributed to fungi upon animals other than man? Clearly instinct preserves animals from many dangers. It may be presumed that under ordinary circumstances there is not much fear of a cow or a sheep poisoning itself in a pasture or a wood. But under extraordinary circumstances it is not only possible, but very probable, that injuries may occur. For instance, it is well known that not only rye and wheat, but also many of the grasses, are liable to infection from a peculiar form of fungus called "ergot." In certain seasons this ergot is much more common than others, and the belief is strong in those who ought to know something of the subject from experience, viz., farmers and graziers, that in such seasons it is not uncommon for cattle to slip their young through feeding on ergotized grass. Then, again, it is fairly open to inquiry whether, in years when "red rust" and "mildew" are more than usually plentiful on grasses, these may not be to a certain extent injurious. Without attempting to associate the cattle plague in any way with fungi on grass, it is nevertheless a most remarkable coincidence that the year in which the cattle disease was most prevalent in this country was one in which there was—at least in some districts—more "red rust" on grasses than we ever remember to have seen before or since; the clothes of a person walking through the rusty field soon became orange-coloured from the abundance of spores. Graziers on this point again seem to be generally agreed, that they do not think "red rust" has been proved to be injurious to cattle. The direct influence of fungi on quadrupeds, birds, reptilia, &c., seems to be infinitesimally small.

Insects of various orders have been observed from time to time to become the prey of fungi.[L] That known at Guadaloupe under the name of La Guepe Vegetale, or vegetable wasp, has been often cited as evidence that, in some instances at least, the fungus attacks the insect whilst still living. Dr. Madianna states that he has noticed the wasp still living with its incumbrance attached to it, though apparently in the last stage of existence, and seeming about to perish from the influence of its destructive parasite.[M] This fungus is called by Tulasne Torrubia sphecocephala.[N] About twenty-five species of this genus of sphaeriaceous fungi have been described as parasitic on insects. Five species are recorded in South Carolina, one in Pennsylvania, found on the larvae of the May-bug, and one other North American species on Nocturnal Lepidoptera, one in Cayenne, one in Brazil, on the larva of a Cicada, and one on a species of ant, two in the West Indies, one in New Guinea on a species of Coccus, and one on a species of Vespa in Senegal. In Australia two species have been recorded, and two are natives of New Zealand. Dr. Hooker found two in the Khassya mountains of India, and one American species has also been found at Darjeeling. It has long been known that one species, which has a medicinal repute there, is found in China, whilst three have been recorded in Great Britain. Opinions are divided as to whether in these instances the fungus causes or is subsequent to the death of the insect. It is generally the belief of entomologists that the death of the insect is caused by the fungus. In the case of Isaria sphingum, which is the conidia form of a species of Torrubia, the moth has been found standing on a leaf, as during life, with the fungus sprouting from its body.

Other and less perfect forms of fungi also attack insects. During the summer of 1826, Professor Sebert collected a great many caterpillars of Arctia villica, for the purpose of watching their growth. These insects on arriving at their full size became quite soft, and then suddenly died. Soon after they became hard, and, if bent, would easily break into two pieces. Their bodies were covered with a beautiful shining white mould. If some of the caterpillars affected with the parasitic mould were placed on the same tree with those apparently free from its attack, the latter soon exhibited signs that they also were attacked in the same manner, in consequence of coming into contact with each other.[O]

During the spring of 1851, some twelve or twenty specimens were found from amongst myriads of Cicada septemdecim, which, though living, had the posterior third of the abdominal contents converted into a dry, powdery, ochreous-yellow compact mass of sporuloid bodies. The outer coverings of that portion of the insect were loose and easily detached, leaving the fungoid matter in the form of a cone affixed by its base to the unaffected part of the abdomen of the insect. The fungus may commence, says Dr. Leidy, its attacks upon the larva, develop its mycelium, and produce a sporular mass within the active pupa, when many are probably destroyed; but should some be only affected so far as not to destroy the organs immediately essential to life, they might undergo their metamorphosis into the imago, in which case they would be affected in the manner previously described.[P]

The common house-fly in autumn is very usually subject to the attacks of a mouldy fungus called Sporendonema muscae, or Empusa muscae in former times, which is now regarded as the terrestrial condition of one of the Saprolegniei.[Q] The flies become sluggish, and at last fix themselves to some object on which they die, with their legs extended and head depressed, the body and wings soon becoming covered with a minute white mould, the joints of which fall on the surrounding object. Examples are readily distinguished when they settle on windows and thus succumb to their foe. Mr. Gray says that a similar mould has been observed on individuals of the wasp family.

A Gryllotalpa was found in a wood near Newark, Delaware, U. S., upon turning over a log. The insect was seen standing very quietly at the mouth of its oval cell, which is formed in the earth, having a short curved tube to the surface. Upon taking it up it exhibited no signs of movement, though perfectly fresh and lifelike in appearance. On examining it next morning it still presented no signs of life. Every part of the insect was perfect, not even the antennae being broken. Upon feeling it, it was very hard and resistant, and on making an incision through the thorax it exhaled a fungoid odour. The insect had been invaded by a parasitic fungus which everywhere filled the animal, occupying the position of all the soft tissue, and extending even into the tarsal joints. It formed a yellowish or cream-coloured compact mass.[R]

The destructive silk-worm disease, Botrytis Bassiana, is also a fungus which attacks and destroys the living insect, concerning which an immense deal has been written, but which has not yet been eradicated. It has also been supposed that a low form or imperfect condition of a mould has much to do with the disease of bees known as "foul brood."[S]

Penicillium Fieberi, figured by Corda on a beetle, was doubtless developed entirely after death, with which event it had probably nothing whatever to do.[T] Sufficient, however, has been written to show that fungi have an influence on insect life, and this might be extended to other animal forms, as to spiders, on which one or two species of Isaria are developed, whilst Dr. Leidy has recorded observations on Julus[U] which may be perused with advantage. Fish are subject to a mouldy-looking parasite belonging to the Saprolegniei, and a similar form attacks the ova of toads and frogs. Gold fish in globes and aquaria are very subject to attack from this mouldy enemy, and although we have seen them recover under a constant change of water, this is by no means always the case, for in a few weeks the parasite will usually prevail.

The influence of fungi upon animals in countries other than European is very little known, except in the case of the species of Torrubia found on insects, and the diseases to which silkworms are subject. Instances have been recorded of the occurrence of fungoid mycelium—for in most it is nothing more—in the tissues of animals, in the hard structure of bone and shell, in the intestines, lungs, and other fleshy parts, and in various organs of birds.[V] In some of the latter cases it has been described as a Mucor, in most it is merely cells without sufficient character for determination. It is by no means improbable that fungi may be found in such situations; the only question with regard to them is whether they are not accidental, and not the producers of unhealthy or diseased tissues, even when found in proximity thereto.

There is one phase of the influences of fungi on the lower animals which must not be wholly passed over, and that is the relation which they bear to some of the insect tribes in furnishing them with food. It is especially the case with the Coleoptera that many species seem to be entirely dependent on fungi for existence, since they are found in no other situations. Beetle-hunters tell us that old Polyporei, and similar fungi of a corky or woody nature, are always sought after for certain species which they seek in vain elsewhere,[W] and those who possess herbaria know how destructive certain minute members of the animal kingdom are to their choicest specimens, against whose depredations even poison is sometimes unavailing.

Some of the Uredines, as Trichobasis suaveolens and Coleosporium sonchi, are generally accompanied by a little orange larva which preys upon the fungus; and in the United States Dr. Bolles informs us that some species of AEcidium are so constantly infested with this red larva that it is scarcely possible to get a good specimen, or to keep it from its sworn enemy. Minute Anguillidae revel in tufts of mould, and fleshy Agarics, as they pass into decay, become colonies of insect life. Small Lepidoptera, belonging to the Tineina, appear to have a liking for such Polyporei as P. sulfureus when it becomes dry and hard, or P. squamosus when it has attained a similar condition. Acari and Psocidae attack dried fungi of all kinds, and speedily reduce them to an unrecognizable powder.

III. What are the influences exerted by fungi on other plants? This is a broad subject, but withal an important one, since these influences act indirectly on man as well as on the lower animals. On man, inasmuch as it interferes with the vegetable portion of his food, either by checking its production or depreciating its quality. On the lower animals, since by this means not only is their natural food deteriorated or diminished, but through it injurious effects are liable to be produced by the introduction of minute fungi into the system. These remarks apply mainly to fungi which are parasitic on living plants. On the other hand, the influence of fungi must not be lost sight of as the scavengers of nature when dealing with dead and decaying vegetable matter. Therefore, as in other instances, we have here also good and bad influences intermingled, so that it cannot be said that they are wholly evil, or unmixed good.

Wherever we encounter decaying vegetable matter we meet with fungi, living upon and at the expense of decay, appropriating the changed elements of previous vegetable life to the support of a new generation, and hastening disintegration and assimilation with the soil. No one can have observed the mycelium of fungi at work on old stumps, twigs, and decayed wood, without being struck with the rapidity and certainty with which disintegration is being carried on. The gardener casts on one side, in a pile as rubbish, twigs and cuttings from his trees, which are useless to him, but which have all derived much from the soil on which they flourished. Shortly fungi make their appearance in species almost innumerable, sending their subtle threads of mycelium deep into the tissues of the woody substance, and the whole mass teems with new life. In this metamorphosis as the fungi flourish so the twigs decay, for the new life is supported at the expense of the old, and together the destroyers and their victims return as useful constituents to the soil from whence they were derived, and form fresh pabulum for a succeeding season of green leaves and sweet flowers. In woods and forests we can even more readily appreciate the good offices of fungi in accelerating the decay of fallen leaves and twigs which surround the base of the parent trees. In such places Nature is left absolutely to her own resources, and what man would accomplish in his carefully attended gardens and shrubberies must here be done without his aid. What we call decay is merely change; change of form, change of relationship, change of composition; and all these changes are effected by various combined agencies—water, air, light, heat, these furnishing new and suitable conditions for the development of a new race of vegetables. These, by their vigorous growth, continue what water and oxygen, stimulated by light and heat, had begun, and as they flourish for a brief season on the fallen glories of the past summer, make preparation for the coming spring.

Unfortunately this destructive power of fungi over vegetable tissues is too often exemplified in a manner which man does not approve. The dry rot is a name which has been given to the ravages of more than one species of fungus which flourishes at the expense of the timber it destroys. One of these forms of dry rot fungus is Merulius lacrymans, which is sometimes spoken of as if it were the only one, though perhaps the most destructive in houses. Another is Polyporus hybridus, which attacks oak-built vessels;[X] and these are not the only ones which are capable of mischief. It appears that the dry rot fungus acts indirectly on the wood, whose cells are saturated with its juice, and in consequence lose their lignine and cellulose, though their walls suffer no corrosion. The different forms of decay in wood are accompanied by fungi, which either completely destroy the tissue, or alter its nature so much by the abstraction of the cellulose and lignine, that it becomes loose and friable. Thus fungi induce the rapid destruction of decaying wood. These are the conclusions determined by Schacht, in his memoir on the subject.[Y]

We may allude, in passing, to another phase of destructiveness in the mycelium of fungi, which traverse the soil and interfere most injuriously with the growth of shrubs and trees. The reader of journals devoted to horticulture will not fail to notice the constant appeals for advice to stop the work of fungi in the soil, which sometimes threatens vines, at others conifers, and at others rhododendrons. Dead leaves, and other vegetable substances, not thoroughly and completely decayed, are almost sure to introduce this unwelcome element.

Living plants suffer considerably from the predations of parasitic species, and foremost amongst these in importance are those which attack the cereals. The corn mildew and its accompanying rust are cosmopolitan, as far as we know, wherever corn is cultivated, whether in Australia or on the slopes of the Himalayas. The same may also be said of smut, for Ustilago is as common in Asia and America as in Europe. We have seen it on numerous grasses as well as on barley from the Punjab, and a species different from Ustilago maydis on the male florets of maize from the same locality. In addition to this, we learn that in 1870 one form made its appearance on rice. It was described as constituting in some of the infested grains a whitish, gummy, interlaced, ill-defined, thread-like mycelium, growing at the expense of the tissues of the affected organs, and at last becoming converted into a more or less coherent mass of spores, of a dirty green colour, on the exterior of the deformed grains. Beneath the outer coating the aggregated spores are of a bright orange red; the central portion has a vesicular appearance, and is white in colour.[Z] It is difficult to determine from the description what this so-called Ustilago may be, which was said to have affected a considerable portion of the standing rice crop in the vicinity of Diamond Harbour.

Bunt is another pest (Tilletia caries) which occupies the whole farinaceous portion of the grains of wheat. Since dressing the seed wheat has been so widely adopted in this country, this pest has been of comparatively little trouble. Sorghum and the small millets, in countries where these are cultivated for food, are liable to attacks from allied parasites. Ergot attacks wheat and rice as well as rye, but not to such an extent as to have any important influence upon the crop. Two or three other species of fungi are sometimes locally troublesome, as Dilophospora graminis, and Septoria nodorum on wheat, but not to any considerable extent. In countries where maize is extensively grown it has not only its own species of mildew (Puccinia), but also one of the most enormous and destructive species of Ustilago.

A singular parasite on grasses was found by Cesati in Italy, in 1850, infesting the glumes of Andropogon.[a] It received the name of Cerebella Andropogonis, but it never appears to have increased and spread to such an extent as was at first feared.

Even more destructive than any of these is the potato disease[b] (Peronospora infestans), which is, unfortunately, too well known to need description. This disease was at one time attributed to various causes, but long since its ascertained source has been acknowledged to be a species of white mould, which also attacks tomatoes, but less vigorously. De Bary has given considerable attention to this disease, and his opinions are clearly detailed in his memoir on Peronospora, as well as in his special pamphlet on the potato disease.[c] One sees the cause of the epidemic, he says, in the diseased state of the potato itself, produced either accidentally by unfavourable conditions of soil and atmosphere, or by a depravation that the plant has experienced in its culture. According to these opinions, the vegetation of the parasite would be purely accidental, the disease would be independent of it, the parasite would be able frequently even to spare the diseased organs. Others see in the vegetation of the Peronospora the immediate or indirect cause of the various symptoms of the disease; either that the parasite invades the stalks of the potato, and in destroying them, or, so to speak, in poisoning them, determines a diseased state of the tubercles, or that it introduces itself into all the organs of the plant, and that its vegetation is the immediate cause of all the symptoms of the disease that one meets with in any organ whatever. His observations rigorously proved that the opinions of the latter were those only which were well founded. All the alterations seen on examining spontaneous individuals are found when the Peronospora is sown in a nourishing plant. The most scrupulous examination demonstrates the most perfect identity between the cultivated and spontaneous individuals as much in the organization of the parasite as in the alteration of the plant that nourishes it. In the experiments that he had made he affirms that he never observed an individual or unhealthy predisposition of the nourishing plant. It appeared to him, on the contrary, that the more the plant was healthy, the more the mould prospered.

We cannot follow him through all the details of the growth and development of the disease, or of his experiments on this and allied species, which resulted in the affirmation that the mould immediately determines the disease of the tubercles as well as that of the leaves, and that the vegetation of the Peronospora alone determines the redoubtable epidemic to which the potato is exposed.[d] We believe that this same observer is still engaged in a series of observations, with the view, if possible, of suggesting some remedy or mitigation of the disease.

Dr. Hassall pointed out, many years since, the action of fungous mycelium, when coming in contact with cellular tissue, of inducing decomposition, a fact which has been fully confirmed by Berkeley.

Unfortunately there are other species of the same genus of moulds which are very destructive to garden produce. Peronospora gangliformis, B., attacks lettuces, and is but too common and injurious. Peronospora effusa, Grev., is found on spinach and allied plants. Peronospora Schleideniana, D. By., is in some years very common and destructive to young onions, and field crops of lucerne are very liable to attack from Peronospora trifoliorum, D. By.

The vine crops are liable to be seriously affected by a species of mould, which is but the conidia form of a species of Erysiphe. This mould, known under the name of Oidium Tuckeri, B., attacks the vines in hothouses in this country, but on the Continent the vineyards often suffer severely[e] from its depredations; unfortunately, not the only pest to which the vine is subject, for an insect threatens to be even more destructive.

Hop gardens suffer severely, in some years, from a similar disease; in this instance the mature or ultimate form is perfected. The hop mildew is Sphaerotheca Castagnei, Lev., which first appears as whitish mouldy blotches on the leaves, soon becoming discoloured, and developing the black receptacles on either surface of the leaf. These may be regarded as the cardinal diseases of fungoid origin to which useful plants are subject in this country.

Amongst those of less importance, but still troublesome enough to secure the anathemas of cultivators, may be mentioned Puccinia Apii, Ca., often successful in spoiling beds of celery by attacking the leaves; Cystopus candidus, Lev., and Glaeosporium concentricum, Grev., destructive to cabbages and other cruciferous plants; Trichobasis Fabae, Lev., unsparing when once established on beans; Erysiphe Martii, Lev., in some seasons a great nuisance to the crop of peas.

Fruit trees do not wholly escape, for Roestelia cancellata, Tul., attacks the leaves of the pear. Puccinia prunorum affects the leaves of almost all the varieties of plum. Blisters caused by Ascomyces deformans, B., contort the leaves of peaches, as Ascomyces bullatus, B., does those of the pear, and Ascomyces juglandis, B., those of the walnut. Happily we do not at present suffer from Ascomyces pruni, Fchl., which, on the Continent, attacks young plum-fruits, causing them to shrivel and fall. During the past year pear-blossoms have suffered from what seems to be a form of Helminthosporium pyrorum, and the branches are sometimes infected with Capnodium elongatum; but orchards in the United States have a worse foe in the "black knot,"[f] which causes gouty swellings in the branches, and is caused by the Sphaeria morbosa of Schweinitz.

Cotton plants in India[g] were described by Dr. Shortt as subject to the attacks of a kind of mildew, which from the description appeared to be a species of Erysiphe, but on receiving specimens from India for examination, we found it to be one of those diseased conditions of tissue formerly classed with fungi under the name of Erineum; and a species of Torula attacks cotton pods after they are ripe. Tea leaves in plantations in Cachar have been said to suffer from some sort of blight, but in all that we have seen insects appear to be the depredators, although on the decaying leaves Hendersonia theicola, Cooke, establishes itself.[h] The coffee plantations of Ceylon suffer from the depredations of Hemiliea vastatrix, as well as from insects.[i] Other useful plants have also their enemies in parasitic fungi.

Olive-trees in the south of Europe suffer from the attacks of a species of Antennaria, as do also orange and lemon trees from a Capnodium, which covers the foliage as if with a coating of soot. In fact most useful plants appear to have some enemy to contend with, and it is fortunate, not only for the plant, but its cultivators, if this enemy is less exacting than is the case with the potato, the vine, and the hop.

Forestry in Britain is an insignificant interest compared to what it is in some parts of Europe, in the United States, and in our Indian possessions. In these latter places it becomes a matter of importance to inquire what influence fungi exert on forest trees. It may, however, be predicated that the injury caused by fungi is far outstripped by insects, and that there are not many fungi which become pests in such situations. Coniferous trees may be infested with the species of Peridermium, which are undoubtedly injurious, Peridermium elatinum, Lk., distorting and disfiguring the silver fir, as Peridermium Thomsoni, B.,[j] does those of Abies Smithiana in the Himalayas. This species occurred at an elevation of 8,000 feet. The leaves become reduced in length one-half, curved, and sprinkled, sometimes in double rows, with the large sori of this species, which gives the tree a strange appearance, and at length proves fatal, from the immense diversion of nutriment requisite to support a parasite so large and multitudinous. The dried specimens have a sweet scent resembling violets. In Northern Europe Caeoma pinitorquum, D. By., seems to be plentiful and destructive. All species of juniper, both in Europe and the United States, are liable to be attacked and distorted by species of Podisoma[k] and Gymnosporangium. Antennaria pinophila, Fr., is undoubtedly injurious, as also are other species of Antennaria, which probably attain their more complete development in Capnodium, of which Capnodium Citri is troublesome to orange-trees in the south of Europe, and other species to other trees. How far birch-trees are injured by Dothidea betulina, Fr., or Melampsora betulina, Lev., or poplars and aspens by Melampsora populina, Lev., and Melampsora tremulae, Lev., we cannot say. The species of Lecythea found on willow leaves have decidedly a prejudicial effect on the growth of the affected plant.

Floriculture has to contend with many fungoid enemies, which sometimes commit great ravages amongst the choicest flowers. Roses have to contend against the two forms of Phragmidium mucronatum as well as Asteroma Rosae. Still more disastrous is a species of Erysiphei, which at first appears like a dense white mould. This is named Sphaerotheca pannosa. Nor is this all, for Peronospora sparsa, when it attacks roses in conservatories, is merciless in its exactions.[l] Sometimes violets will be distorted and spoiled by Urocystis Violae. The garden anemone is freely attacked by AEcidium quadrifidum. Orchids are liable to spot from fungi on the leaves, and recently the whole of the choicest hollyhocks have been threatened with destruction by a merciless foe in Puccinia malvacearum. This fungus was first made known to the world as an inhabitant of South America many years ago. It seems next to have come into notoriety in the Australian colonies. Then two or three years ago we hear of it for the first time on the continent of Europe, and last year for the first time in any threatening form in our own islands. During the present year its ravages are spreading, until all admirers of hollyhocks begin to feel alarm lest it should entirely exterminate the hollyhock from cultivation. It is common on wild mallows, and cotton cultivators must be on the alert, for there is a probability that other malvaceous plants may suffer.

A writer in the "Gardener's Chronicle" has proposed a remedy for the hollyhock disease, which he hopes will prove effectual. He says, "This terrible disease has now, for twelve months, threatened the complete annihilation of the glorious family of hollyhock, and to baffle all the antidotes that the ingenuity of man could suggest, so rapidly does it spread and accomplish its deadly work. Of this I have had very sad evidence, as last year at this time I had charge of, if not the largest, one of the largest and finest collections of hollyhocks anywhere in cultivation, which had been under my special care for eleven years, and up to within a month of my resigning that position I had observed nothing uncommon amongst them; but before taking my final leave of them I had to witness the melancholy spectacle of bed after bed being smitten down, and amongst them many splendid seedlings, which had cost me years of patience and anxiety to produce. And again, upon taking a share and the management of this business, another infected collection fell to my lot, so that I have been doing earnest battle with this disease since its first appearance amongst us, and I must confess that, up to a very short time back, I had come in for a great deal the worst of the fight, although I had made use of every agent I could imagine as being likely to aid me, and all that many competent friends could suggest. But lately I was reminded of Condy's patent fluid, diluted with water, and at once procured a bottle of the green quality, and applied it in the proportion of a large tablespoonful to one quart of water, and upon examining the plants dressed, twelve hours afterwards, was delighted to find it had effectually destroyed the disease (which is easily discernible, as when it is living and thriving it is of a light grey colour, but when killed it becomes of a rusty black). Further to test the power at which the plant was capable of bearing the antidote without injury, I used it double the strength. This dose was instant death to the pest, leaving no trace of any injury to the foliage. As to its application, I advocate sponging in all dressings of this description. Syringing is a very ready means, but very wasteful. No doubt sponging consumes more time, but taking into consideration the more effectual manner in which the dressing can be executed alone, it is in the end most economical, especially in regard to this little parasite. I have found it difficult by syringing, as it has great power of resisting and throwing off moisture, and if but a very few are left living, it is astonishing how quickly it redistributes itself. I feel confident, that by the application of this remedy in time another season, I shall keep this collection clean. I believe planting the hollyhock in large crowded beds should be avoided, as I have observed the closer they are growing the more virulently does the disease attack them, whereas isolated rows and plants are but little injured."[m]

The "Gardener's Chronicle" has also sounded a note of warning that a species of Uredine has been very destructive to pelargoniums at the Cape of Good Hope. Hitherto these plants have not suffered much in this country from parasites. Besides these, there are many other less troublesome parasites, such as Uredo filicum, on ferns; Puccinia Lychnidearum, on leaves of sweet-william; Uredo Orchidis, on leaves of orchids, &c.

If we would sum up the influences of fungi in a few words, it could be done somewhat in the following form.

Fungi exert a deleterious influence—

On Man,

When eaten inadvertently. By the destruction of his legitimate food. In producing or aggravating skin diseases.

On Animals,

By deteriorating or diminishing their food supplies. By establishing themselves as parasites on some species.

On Plants,

By hastening the decay of timber. By establishing themselves as parasites. By impregnating the soil.

But it is not proved that they produce epidemic diseases in man or animals, or that the dissemination of their multitudinous spores in the atmosphere has any appreciable influence on the health of the human race. Hence their association with cholera, diarrhoea, measles, scarlatina, and the manifold ills that flesh is heir to, as producing or aggravating causes, must, in the present state of our knowledge and experience, be deemed apocryphal.

[A] A detailed account of the peculiar properties of this fungus and its employment as a narcotic will be found in Cooke's "Seven Sisters of Sleep," p. 337. It is figured in Greville's "Scottish Cryptogamic Flora," plate 54.

[B] Pour chaque 500 grammes de champignons coupes en morceaux d'assez mediocre grandeur, il faut un litre d'eau acidulee par deux ou trois cuillerees de vinaigre, ou deux cuillerees de sel gris. Dans le cas ou l'on n'aurait que de l'eau a sa disposition, il faut la renouveler une ou deux fois. On laisse les champignons macerer dans le liquids pendant deux heures entieres, puis on les lave a grande eau. Ils sont alors mis dans de l'eau froide qu'on porte a l'ebullition, et apres un quart d'heure ou une demi-heure, on les retire, on les lave, on les essuie, et ou les apprete soit comme un mets special, et ils comportent les memes assaisonnements que les autres, soit comme condiment.—Morel Traite des Champignons, p. lix. Paris, 1865.