[Footnote 1: Die Lehre von den Lagerstatten der Erze, von Dr. Albrecht von Groddek, Leipzig. 1879.]

[Footnote 2: Untersuchungen uber Erzgange, von Fridolin Sandberger, Weisbaden, 1882.]

[Footnote 3: Geology and Mining Industry of Leadville, Annual Report, Director U.S. Geol. Surv., 1881.]

[Footnote 4: Geology of the Comstock Lode and Washoe District, G.F. Becker, Washington, 1883.

It is but justice to Messrs. Becker and Emmons to say that theirs are admirable studies, thorough and exhaustive, of great interest and value to both mining engineers and geologists, and most creditable to the authors and the country. No better work of the kind has been done anywhere, and it will detract little from its merit even if the views of the authors on the theoretical question of the sources of the ores shall not be generally adopted.]

The lack of space must forbid the full discussion of these theories at the present time, but I will briefly enumerate some of the facts which render it difficult for me to accept them.

First, the great diversity of character exhibited by different sets of fissure veins which cut the same country rock seems incompatible with any theory of lateral secretion. These distinct systems are of different ages, of diversified composition, and have evidently drawn their supply of material from different sources. Hundreds of cases of this kind could be cited, but I will mention only a few; among others the Humboldt, the Bassick, and the Bull Domingo, near Rosita and Silver Cliff, Colorado. These are veins contained in the same sheet of eruptive rock, but the ores are as different as possible. The Humboldt is a narrow fissure carrying a thin ore streak of high grade, consisting of sulphides of silver, antimony, arsenic, and copper; the Bassick is a great conglomerate vein containing tellurides of silver and gold, argentiferous galena, blende, and yellow copper; the Bull Domingo is also a great fissure filled with rubbish containing ore chimneys of galena with tufts of wire silver. I may also cite the Jordan, with its intersecting and yet distinct and totally different veins; the Galena, the Neptune, and the American Flag, in Bingham Canon, Utah; and the closely associated yet diverse system of veins the Ferris, the Washington, the Chattanooga, the Fillmore, etc., in Bullion Canon at Marysvale. In these and many other groups which have been examined by the writer, the same rocks are cut by veins of different ages, having different bearings, and containing different ores and veinstones. It seems impossible that all these diversified materials should have been derived from the same source, and the only rational explanation of the phenomena is that which I have heretofore advocated, the ascent of metalliferous solutions from different and deep seated sources.

Another apparently unanswerable argument against the theory of lateral secretion is furnished by the cases where the same vein traverses a series of distinct formations, and holds its character essentially unaffected by changes in the country rock. One of many such may be cited in the Star vein at Cherry Creek, Nevada, which, nearly at right angles to their strike, cuts belts of quartzite, limestone, and slate, maintaining its peculiar character of ore and gangue throughout.

This and all similar veins have certainly been filled with material brought from a distance, and not derived from the walls.

LEACHING OF IGNEOUS ROCKS.

The arguments against the theory that mineral veins have been produced by the leaching of superficial igneous rocks are in part the same as those already cited against the general theory of lateral secretion. They may be briefly summarized as follows:

1. Thousands of mineral veins in this and other countries occur in regions remote from eruptive rocks. Into this category come most of those of the eastern half of the Continent, viz., Canada, New England, the Alleghany belt, and the Mississippi Valley. Among those I will refer only to a few selected to represent the greatest range of character, viz., the Victoria lead mine, near Sault Ste. Marie, the Bruce copper mine on Lake Huron, the gold-bearing quartz veins of Madoc, the Gatling gold vein of Marmora, the Acton and the Harvey Hill copper mines of Canada, the copper veins of Ely, Vermont, and of Blue Hills, Maine, the silver-bearing lead veins of Newburyport, Mass.; most of the segregated gold veins of the Alleghany belt, the lead veins of Rossie, Ellenville, and at other localities farther South; the copper bearing veins of Virginia, North Carolina, and Tennessee; the veins carrying argentiferous galena in Central Kentucky and in Southern Illinois; the silver, copper, and antimony veins of Arkansas; and the lead and zinc deposits of Missouri and the Upper Mississippi.

In these widely separated localities are to be found fissure, segregated, and gash veins, and a great diversity of ores, which have been derived, sometimes from the adjacent rocks—as in the segregated veins of the Alleghany belt and the gash veins of the Mississippi region—and in other cases—where they are contained in true fissure veins—from a foreign source, but all deposited without the aid of superficial igneous rocks, either as contributors of matter or force.

2. In the great mineral belt of the Far West, where volcanic emanations are so abundant, and where they have certainly played an important part in the formation of ore deposits, the great majority of veins are not in immediate contact with trap rocks, and they could not, therefore, have furnished the ores.

A volume might be formed by a list of the cases of this kind, but I can here allude to a few only, most of which I have myself examined, viz.:

(a.) The great ore chambers of the San Carlos Mountains in Chihuahua, the largest deposits of ore of which I have any knowledge. These are contained in heavy beds of limestone, which are cut in various places by trap dikes, which, as elsewhere, have undoubtedly furnished the stimulus to chemical action that has resulted in the formation of the ore bodies, but are too remote to have supplied the material.

(b.) The silver mines of Santa Eulalia, in Chihuahua, from which during the last century one hundred and twelve millions of dollars were taken, opened on ore deposits situated in Cretaceous limestones like those of San Carlos, and apparently similar ore-filled chambers; an igneous rock caps the hills in the vicinity, but is nowhere in contact or even proximity to the ore bodies. (See Kimball, Amer. Jour. Sci,. March, 1870.)

(c.) The great chambers of Tombstone, and the copper veins of the Globe District, the Copper Queen, etc., in Arizona.

(d.) The large bodies of silver-ore at Lake Valley, New Mexico; chambers in limestone, like c.

(e.) The Black Hawk group of gold mines, the Montezuma, Georgetown, and other silver mines in the granite belt of Colorado.

(f.) The great group of veins and chambers in the Bradshaw, Lincoln, Star, and Granite districts of Southern Utah, where we find a host of veins of different character in limestone or granite, with no trap to which the ores can be credited.

(g.) The Crismon Mammoth vein of Tintic.

(h.) The group of mines opened on the American Fork, on Big and Little Cottonwood, and in Parley's Park, including the Silver Bell, the Emma, the Vallejo, the Prince of Wales, the Kessler, the Bonanza, the Climax, the Pinon, and the Ontario. (The latter, the greatest silver mine now known in the country, lies in quartzite, and the trap is near, but not in contact with the vein.)

(i.) In Nevada, the ore deposits of Pioche, Tempiute, Tybo, Eureka, White Pine, and Cherry Creek, on the east side of the State, with those of Austin, Belmont, and a series too great for enumeration in the central and western portions.

(j.) In California, the Bodie, Mariposa, Grass Valley, and other mines.[1]

(k.) In Idaho, those of the Poor Man in the Owyhee district, the principal veins of the Wood River region, the Ramshorn at Challis, the Custer and Charles Dickens, at Bonanza City, etc.

[Footnote 1: See Redmond's Report (California Geol. Survey Mining Statistics, No 1), where seventy-seven mines are enumerated, of which three are said to be in "porphyritic schist," all the others in granite, mica schist, clay, slate, etc.]

In nearly all these localities we may find evidence not only that the ore deposits have not been derived from the leaching of igneous rocks, but also that they have not come from those of any kind which form the walls of the veins.

The gold-bearing quartz veins of Deadwood are so closely associated with dikes of porphyry, that they may have been considered as illustrations of the potency of trap dikes in producing concentration of metals. But we have conclusive evidence that the gold was there in Archaean times, while the igneous rocks are all of modern, probably of Tertiary, date. This proof is furnished by the "Cement mines" of the Potsdam sandstone. This is the beach of the Lower Silurian sea when it washed the shores of an Archaean island, now the Black Hills. The waves that produced this beach beat against cliffs of granite and slate containing quartz veins carrying gold. Fragments of this auriferous quartz, and the gold beaten out of them and concentrated by the waves, were in places buried in the sand beach in such quantity as to form deposits from which a large amount of gold is now being taken. Without this demonstration of the origin and antiquity of the gold, it might very well have been supposed to be derived from the eruptive rock.

Strong arguments against the theory that the leaching of superficial igneous rocks has supplied the materials filling mineral veins, are furnished by the facts observed in the districts where igneous rocks are most prevalent, viz.: (1.) Such districts are proverbially barren of useful minerals. (2.) Where these occur, the same sheet of rock may contain several systems of veins with different ores and gangues.

The great lava plain of Snake River, the Pedrigal country of eastern Oregon, Northern California and Mexico are without valuable ore deposits. The same may be said of the Pancake Range and other mountain chains of igneous rock in Nevada, while the adjacent ranges composed of sedimentary rocks are rich in ore deposits of various kinds. A still stronger case is furnished by the Cascade Mountains, which, north of the California line, are composed almost exclusively of erupted material, and yet in all this belt, so far as now known, not a single valuable mine has been opened. In contrast with this is the condition of things in California, where the Sierra Nevada is composed of metamorphic rocks which have been shown to be the repositories of vast quantities of gold, silver, and copper. Cases belonging to this category may be found at Rosita and Silver Cliff, where the diversity in the ores of the mines already enumerated can hardly be reconciled with the theory of a common origin. At Lake City the prevailing porphyry holds the veins of the Ute and Ulay and the Ocean Wave mines, which are similar, and the Hotchkiss, the Belle, etc., entirely different.

We have no evidence that any volcanic eruption has drawn its material from zones or magmas especially rich in metals or their ores, and on the contrary, volcanic districts, like those mentioned, and regions, such as the Sandwich Islands, where the greatest, eruptions have taken place, are poorest in metalliferous deposits.

All the knowledge we have of the subject justifies the inference that most of the igneous rocks which have been poured out in our Western Territories are but fused conditions of sediments which form the substructure of that country. Over the great mineral belt which lies between the Sierra Nevada and the front range of the Rocky Mountains, and extends not only across the whole breadth of our territory, but far into Mexico, the surface was once underlain by a series of Palaeozoic sedimentary strata not less than twenty to thirty thousand feet in thickness; and beneath these, at the sides, and doubtless below, were Archaeun rocks, also metamorphosed sediments. Through these the ores of the metals were generally though sparsely distributed. In the convulsions which have in recent times broken up this so long quiet and stable portion of the earth's crust (and which have resulted in depositing in thousands of cracks and cavities the ores we now mine), portions of the old table-land were in places set up at high angles forming mountain chains, and doubtless extending to the zone of fusion below. Between these blocks of sedimentary rocks oozed up through the lines of fracture quantities of fused material, which also sometimes formed mountain chains; and it is possible and even probable that the rocks composing the volcanic ridges are but phases of the same materials that form the sedimentary chains There is, therefore, no a priori reason why the leaching of one group should furnish more ore than the other; but, as a matter of fact, the unfused sediments are much the richer in ore deposits. This can only be accounted for, in my judgment, by supposing that they have been the receptacles of ore brought from a foreign source; and we can at least conjecture where and how gathered. We can imagine, and we are forced to conclude, that there has been a zone of solution below, where steam and hot water, under great pressure, have effected the leaching of ore-bearing strata, and a zone of deposition above, where cavities in pre-existent solidified and shattered rocks became the repositories of the deposits made from ascending solutions, when the temperature and pressure were diminished. Where great masses of fused material were poured out, these must have been for along time too highly heated to become places of deposition; so long indeed that the period of active vein formation may have passed before they reached a degree of solidification and coolness that would permit their becoming receptacles of the products of deposition. On the contrary, the masses of unfused and always relatively cool sedimentary rocks which form the most highly metalliferous mountain ranges (White Pine, Toyabe, etc.) were, throughout the whole period of disturbance, in a condition to become such repositories. Certainly highly heated solutions forced by an irresistible vis a tergo through rocks of any kind down in the heated zone, would be far more effective leaching agents than cold surface water with feeble solvent power, moved only by gravity, percolating slowly through superficial strata.

Richthofen, who first made a study of the Comstock lode, suggests that the mineral impregnation of the vein was the result of a process like that described, viz., the leaching of deep-seated rocks, perhaps the same that inclose the vein above, by highly heated solutions which deposited their load near the surface. On the other hand, Becker supposes the concentration to have been effected by surface waters flowing laterally through the igneous rocks, gathering the precious metals and depositing them in the fissure, as lateral secretion produces the accumulation of ore in the limestone of the lead region. But there are apparently good reasons for preferring the theory of Richthofen: viz., first, the veinstone of the Comstock is chiefly quartz, the natural and common precipitate of hot waters, since they are far more powerful solvents of silica than cold. On the contrary, the ores deposited from lateral secretion, as in the Mississippi lead region, at low temperature contain comparatively little silica; second, the great mineral belt to which reference has been made above is now the region where nearly all the hot springs of the continent are situated. It is, in fact, a region conspicuous for the number of its hot springs, and it is evident that these are the last of the series of thermal phenomena connected with the great volcanic upheavals and eruptions, of which this region has been the theater since the beginning of the Tertiary age. The geysers of Yellowstone Park, the hot springs of the Wamchuck district in Oregon, the Steamboat Springs of Nevada, the geysers of California, the hot springs of Salt Lake City, Monroe, etc., in Utah, and the Pagosa in Colorado, are only the most conspicuous among thousands of hot springs which continue in action at the present time. The evidence is also conclusive that the number of hot springs, great as it now is in this region, was once much greater. That these hot springs were capable of producing mineral veins by material brought up in and deposited from their waters, is demonstrated by the phenomena observable at the Steamboat Springs, and which were cited in my former article as affording the best illustration of vein formation.

The temperature of the lower workings of the Comstock vein is now over 150 deg.F., and an enormous quantity of hot water is discharged through the Sutro Tunnel. This water has been heated by coming in contact with hot rocks at a lower level than the present workings of the Comstock lode, and has been driven upward in the same way that the flow of all hot springs is produced. As that flow is continuous, it is evident that the workings of the Comstock have simply opened the conduits of hot springs, which are doing to-day what they have been doing in ages past, but much less actively, i.e., bringing toward the surface the materials they have taken into solution in a more highly heated zone below. Hence it seems much more natural to suppose that the great sheets of ore-bearing quartz now contained in the Comstock fissure were deposited by ascending currents of hot alkaline waters, than by descending currents of those which were cold and neutral The hot springs are there, though less copious and less hot than formerly, and the natural deposits from hot waters are there. Is it not more rational to suppose with Richthofen that these are related as cause and effect, rather than that cold water has leached the ore and the silica from the walls near the surface? Mr. Becker's preference for the latter hypothesis seems to be due to the discovery of gold and silver in the igneous rocks adjacent to the vein, and yet, except in immediate contact with it, these rocks contain no more of the precious metals than the mere trace which by refined tests may be discovered everywhere. If, as we have supposed, the fissure was for a long time filled with a hot solution charged with an unusual quantity of the precious metals, nothing would be more natural than that the wall rocks should be to some extent impregnated with them.

It will perhaps illuminate the question to inquire which of the springs and water currents of this region are now making deposits that can be compared with those which filled the Comstock and other veins. No one who has visited that country will hesitate to say the hot and not the cold waters. The immense silicious deposits, carrying the ores of several metals, formed by the geysers of the Yellowstone, the Steamboat Springs, etc., show what the hot waters are capable of doing; but we shall search in vain for any evidence that the cold surface waters have done or can do this kind of work.

At Leadville the case is not so plain, and yet no facts can be cited which really prove that the ore deposits have been formed by the leaching of the overlying porphyry rather than by an outflow of heated mineral solutions along the plane of junction between the porphyry and the limestone. Near this plane the porphyry is often thoroughly decomposed, is somewhat impregnated with ore, and even contains sheets of ore within itself; but remote from the plane of contact with the limestone, it contains little diffused and no concentrated ore. It is scarcely more previous than the underlying limestones, and why a solution that could penetrate and leach ores from it should be stopped at the upper surface of the blue limestone is not obvious; nor why the plane of junction between the porphyry and the blue limestone should be the special place of deposit of the ore.

If the assays of the porphyry reported by Mr. Emmons were accurately made, and they shall be confirmed by the more numerous ones necessary to settle the question, and the estimates he makes of the richness of that rock be corroborated, an unexpected result will be reached, and, as I think, a remarkable and exceptional case of the diffusion of silver and lead through an igneous rock be established.

It is of course possible that the Leadville porphyries are only phases of rocks rich in silver, lead, and iron, which underlie this region, and which have been fused and forced to the surface by an ascending mass of deeper seated igneous rock; but even if the argentiferous character of the porphyry shall be proved, it will not be proved that such portions of it as here lie upon the limestone have furnished the ore by the descending percolation of cold surface waters. Deeper lying masses of this same silver, lead, and iron bearing rock, digested in and leached by hot waters and steam under great pressure, would seem to be a more likely source of the ore. If the surface porphyry is as rich in silver as Mr. Emmous reports it to be, it is too rich, for the rock that has furnished so large a quantity of ores as that which formed the ore bodies which I saw in the Little Chief and Highland Chief mines, respectively 90 feet and 162 feet thick, should be poor in silver and iron and lead, and should be rotten from the leaching it had suffered, but except near the ore-bearing contact it is compact and normal.

Such a digested, kaolinized, desilicated rock as we would naturally look for we find in the porphyry near the contact; and its condition there, so different from what it is remote from the contact, seems to indicate an exposure to local and decomposing influences, such indeed as a hot chemical solution forced up from below along the plane of contact would furnish.

It is difficult to understand why the upper portions of the porphyry sheet should be so different in character, so solid and homogeneous, with no local concentrations or pockets of ore, if they have been exposed to the same agencies as those which have so changed the under surface.

Accepting all the facts reported by Mr. Emmons, and without questioning the accuracy of any of his observations, or depreciating in any degree the great value of the admirable study he has made of this difficult and interesting field, his conclusion in regard to the source of the ore cannot yet be insisted on as a logical necessity. In the judgment of the writer, the phenomena presented by the Leadville ore deposits can be as well or better accounted for by supposing that the plane of contact between the limestone and porphyry has been the conduit through which heated mineral solutions coming from deep seated and remote sources have flowed, removing something from both the overlying and underlying strata, and by substitution depositing sulphides of lead, iron, silver, etc., with silica.

The ore deposits of Tybo and Eureka in Nevada, of the Emma, the Cave, and the Horn Silver [1] mines in Utah, have much in common with those of Leadville, and it is not difficult to establish for all of the former cases a foreign and deep seated source of the ore. The fact that the Leadville ore bodies are sometimes themselves excavated into chambers, which has been advanced as proof of the falsity of the theory here advocated, has no bearing on the question, as in the process of oxidation of ores which were certainly once sulphides, there has been much change of place as well as character; currents of water have flowed through them which have collected and redeposited the cerusite in sheets of "hard carbonate" or "sand carbonate," and have elsewhere produced accumulations of kerargyrite, perhaps thousands of years after the deposition of the sulphide ores had ceased and the oxidation had begun. In the leaching and rearrangement of the ore bodies, nothing would be more natural than that accumulations in one place should be attended by the formation of cavities elsewhere.

[Footnote 1: The Horn Silver ore body lies in a fault fissure between a footwall of limestone and a hanging wall of trachyte, and those who consider the Leadville ores as teachings of the overlying porphyry would probably also regard the ore of the Horn Silver mine as derived from the trachyte hanging wall; but three facts oppose the acceptance of this view, viz., let, the trachyte, except in immediate contact with the ore body, seems to be entirely barren; 2d, the Horn Silver ore "chimney," perhaps fifty feet thick, five hundred feet wide, and of unknown depth, is the only mass of ore yet found in a mile of well marked fissure; and 3d, the Carbonate mine opened near by in a strong fissure with a bearing at right angles to that of the Horn Silver, and lying entirely within the trachyte, yields ore of a totally different kind. Both are opened to the depth of seven hundred feet with no signs of change or exhaustion. If the ore were derived from the trachyte, it should be at least somewhat alike in the two mines, should be more generally distributed in the Horn Silver fissure, and might be expected to give out at, no great depth.

If deposited by solutions coming from deep and different sources, the observed differences in character would be natural; it would accumulate as we find it in the channels of outflow, and would be as time will probably prove it, perhaps variable in quantity, but indefinitely continuous in depth.]

Another question which suggests itself in reference to the Leadville deposits is this: If the Leadville ore was once a mass of sulphides derived from the overlying porphyry by the percolation of surface waters, why has the deposit ceased? The deposition of galena, blende, and pyrite in the Galena lead mines still continues. If the leaching of the Leadville porphyry has not resulted in the formation of alkaline sulphide solutions, and the ore has come from the porphyry in the condition of carbonate of lead, chloride of silver, etc., then the nature of the deposition was quite different from that of the similar ones of Tybo, Eureka, Bingham, etc., which are plainly gossans, and indeed is without precedent. But if the process was similar to that in the Galena lead region, and the ores were originally sulphides, their formation should have continued and been detected in the Leadville mines.

For all these reasons the theory of Mr. Emmons will be felt to need further confirmation before it is universally adopted.

From what has gone before it must not be inferred that lateral secretion is excluded by the writer from the list of agencies which have filled mineral veins, for it is certain that the nature of the deposit made in the fissure has frequently been influenced by the nature of the adjacent wall rock. Numerous cases may be cited where the ores have increased or decreased in quantity and richness, or have otherwise changed character in passing from one formation to another; but even here the proof is generally wanting that the vein materials have been furnished by the wall rocks opposite the places where they are found.

The varying conductivity of the different strata in relation to heat and electricity may have been an important factor. Trap dikes frequently enrich veins where they approach or intersect them, and they have often been the primum mobile of vein formation, but chiefly, if not only, by supplying heat, the mainspring of chemical action. The proximity of heated masses of rock has promoted chemical action in the same way as do the Bunsen burners or the sand baths in the laboratory; but no case has yet come under my observation where it was demonstrable that the filling of a fissure vein had been due to secretion from igneous or sedimentary wall rocks.

In the Star District of Southern Utah the country rock is Palaeozoic limestone, and it is cut by so great a number and variety of mineral veins that from the Harrisburg, a central location, a rifle shot would reach ten openings, all on as many distinct and different veins (viz., the Argus, Little Bilk, Clean Sweep, Mountaineer, St. Louis, Xenia, Brant, Kannarrah, Central, and Wateree). The nearest trap rock is half a mile or more distant, a columnar dike perhaps fifteen feet in thickness, cutting the limestone vertically. On either side of this dike is a vein from one to three feet in thickness, of white quartz with specks of ore. Where did that quartz come from? From the limestone? But the limestone contains very little silica, and is apparently of normal composition quite up to the vein. From the trap? This is compact, sonorous basalt, apparently unchanged; and that could not have supplied the silica without complete decomposition.

I should rather say from silica bearing hot waters that flowed up along the sides of the trap, depositing there, as in the numerous and varied veins of the vicinity, mineral matters brought from a zone of solution far below.

To summarize the conclusions reached in this discussion. I may repeat that the results of all recent as well as earlier observations has been to convince me that Richthofen's theory of the filling of the Comstock lode is the true one, and that the example and demonstration of the formation of mineral veins furnished by the Steamboat Springs is not only satisfactory, but typical.

* * * * *

[NATURE.]



HABITS OF BURROWING CRAYFISHES IN THE UNITED STATES.

On May 13, 1883, I chanced to enter a meadow a few miles above Washington, on the Virginia side of the Potomac, at the head of a small stream emptying into the river. It was between two hills, at an elevation of 100 feet above the Potomac, and about a mile from the river. Here I saw many clayey mounds covering burrows scattered over the ground irregularly both upon the banks of the stream and in the adjacent meadow, even as far as ten yards from the bed of the brook. My curiosity was aroused, and I explored several of the holes, finding in each a good-sized crayfish, which Prof. Walter Faxon identified as Cambarus diogenes, Girard (C. obesus, Hagen), otherwise known as the burrowing crayfish. I afterward visited the locality several times, collecting specimens of the mounds and crayfishes, which are now in the United States National Museum, and making observations.

At that time of the year the stream was receding, and the meadow was beginning to dry. At a period not over a month previous, the meadows, at least as far from the stream as the burrows were found, had been covered with water. Those burrows near the stream were less than six inches deep, and there was a gradual increase in depth as the distance from the stream became greater. Moreover, the holes farthest from the stream were in nearly every case covered by a mound, while those nearer had either a very small chimney or none at all, and subsequent visits proved that at that time of year the mounds were just being constructed, for each time I revisited the place the mounds were more numerous.



The length, width, general direction of the burrows, and number of the openings were extremely variable, and the same is true of the mounds. Fig. 1 illustrates a typical burrow shown in section. Here the main burrow is very nearly perpendicular, there being but one oblique opening having a very small mound, and the main mound is somewhat wider than long. Occasionally the burrows are very tortuous, and there are often two or three extra openings, each sometimes covered by a mound. There is every conceivable shape and size in the chimneys, ranging from a mere ridge of mud, evidently the first foundation, to those with a breadth one-half the height. The typical mound is one which covers the perpendicular burrow in Fig. 1, its dimensions being six inches broad and four high. Two other forms are shown in Fig. 2. The burrows near the stream were seldom more than six inches deep, being nearly perpendicular, with an enlargement at the base, and always with at least one oblique opening. The mounds were usually of yellow clay, although in one place the ground was of fine gravel, and there the chimneys were of the same character. They were always circularly pyramidal in shape, the hole inside being very smooth, but the outside was formed of irregular nodules of clay hardened in the sun and lying just as they fell when dropped from the top of the mound. A small quantity of grass and leaves was mixed through the mound, but this was apparently accidental.

The size of the burrows varied from half an inch to two inches in diameter, being smooth for the entire distance, and nearly uniform in width. Where the burrow was far distant from the stream, the upper part was hard and dry. In the deeper holes I invariably found several enlargements at various points in the burrow. Some burrows were three feet deep, indeed they all go down to water, and, as the water in the ground lowers, the burrow is undoubtedly projected deeper. The diagonal openings never at that season of the year have perfect chimneys, and seldom more than a mere rim. In no case did I find any connection between two different burrows. In digging after the inhabitants I was seldom able to secure a specimen from the deeper burrows, for I found that the animal always retreated to the extreme end, and when it could go no farther would use its claws in defense. Both males and females have burrows, but they were never found together, each burrow having but a single individual. There is seldom more than a pint of water in each hole, and this is muddy and hardly suitable to sustain life.



The neighboring brooks and springs were inhabited by another species of crayfish, Cambaras bartonii, but although especial search was made for the burrowing species, in no case was a single specimen found outside of the burrows. C. bartonii was taken both in the swiftly running portions of the stream and in the shallow side pools, as well as in the springs at the head of small rivers. It would swim about in all directions, and was often found under stones and in little holes and crevices, none of which appeared to have been made for the purpose of retreat, but were accidental. The crayfishes would leave these little retreats whenever disturbed, and swim away down stream out of sight. They were often found some distance from the main stream under rocks that had been covered by the brook at a higher watermark; but although there was very little water under the rocks, and the stream had not covered them for at least two weeks, they showed no tendency to burrow. Nor have I ever found any burrows formed by the river species Cumbarus affinis. although I have searched over miles of marsh land on the Potomac for this purpose.



The brook near where my observations were made was fast decreasing in volume, and would probably continue to do so until in July its bed would be nearly dry. During the wet seasons the meadow is itself covered. Even in the banks of the stream, then under water, there were holes, but they all extended obliquely without exception, there being no perpendicular burrows and no mounds. The holes extended in about six inches, and there was never a perpendicular branch, nor even an enlargement at the end. I always found the inhabitant near the mouth, and by quickly cutting off the rear part of the hole could force him out, but unless forcibly driven out it would never leave the hole, not even when a stick was thrust in behind it. It was undoubtedly this species that Dr. Godman mentioned in his "Rambles of a Naturalist," and which Dr. Abbott (Am. Nal., 1873, p. 81) refers to C. bartonii. Although I have no proof that this is so, I am inclined to believe that the burrowing crayfishes retire to the stream in winter and remain there until early spring, when they construct their burrows for the purpose of rearing their young and escaping the summer droughts. My reason for saying this is that I found one burrow which on my first visit was but six inches deep, and later had been projected to a depth at least twice as great, and the inhabitant was an old female.

I think that after the winter has passed, and while the marsh is still covered with water, impregnation takes place and burrows are immediately begun. I do not believe that the same burrow is occupied for more than one year, as it would probably fill up during the winter. At first it burrows diagonally, and as long as the mouth is covered with water is satisfied with this oblique hole. When the water recedes, leaving the opening uncovered, the burrow must be dug deeper, and the economy of a perpendicular burrow must immediately suggest itself. From that time the perpendicular direction is preserved with more or less regularity. Immediately after the perpendicular hole is begun, a shorter opening to the surface is needed for conveying the mud from the nest, and then the perpendicular opening is made. Mud from this, and also from the first part of the perpendicular burrow, is carried out of the diagonal opening and deposited on the edge. If a freshet occurs before this rim of mud has had a chance to harden, it is washed away, and no mound is formed over the oblique burrow.

After the vertical opening is made, as the hole is bored deeper, mud is deposited on the edge, and the deeper it is dug the higher the mound. I do not think that the chimney is a necessary part of the nest, but simply the result of digging. I carried away several mounds, and in a week revisited the place, and no attempt had been made to replace them; but in one case, where I had in addition partly destroyed the burrow by dropping mud into it, there was a simple half rim of mud around the edge, showing that the crayfish had been at work; and as the mud was dry the clearing must have been done soon after my departure. That the crayfish retreats as the water in the ground falls lower and lower is proved by the fact that at various intervals there are bottled-shaped cavities marking the end of the burrow at an earlier period. A few of those mounds farthest from the stream had their mouths closed by a pellet of mud. It is said that all are closed during the summer months.

How these animals can live for months in the muddy, impure water is to me a puzzle. They are very sluggish, possessing none of the quick motions of their allied C. bartonii, for when taken out and placed either in water or on the ground, they move very slowly. The power of throwing off their claws when these are grasped is often exercised. About the middle of May the eggs hatch, and for a time the young cling to the mother, but I am unable to state how long they remain thus. After hatching they must grow rapidly, and soon the burrow will be too small for them to live in, and they must migrate. It would be interesting to know more about the habits of this peculiar species, about which so little has been written. An interesting point to settle would be how and where it gets its food. The burrow contains none, either animal or vegetable. Food must be procured at night, or when the sun is not shining brightly. In the spring and fall the green stalks of meadow grasses would furnish food, but when these become parched and dry they must either dig after and eat the roots, or search in the stream. I feel satisfied that they do not tunnel among the roots, for if they did so these burrows would be frequently met with. Little has as yet been published upon this subject, and that little covers only two spring months—April and May—and it would be interesting if those who have an opportunity to watch the species during other seasons, or who have observed them at any season of the year, would make known their results.

RALPH S. TARR

* * * * *



OUR SERVANTS, THE MICROBES.

Who of us has not, in a partially darkened room, seen the rays of the sun, as they entered through apertures or chinks in the shutters, exhibit their track by lighting up the infinitely small corpuscles contained in the air? Such corpuscles always exist, except in the atmosphere of lofty mountains, and they constitute the dust of the air. A microscopic examination of them is a matter of curiosity. Each flock is a true museum (Fig. 1), wherein we find grains of mineral substances associated with organic debris, and germs of living organisms, among which must be mentioned the microbes.

Since the splendid researches of Mr. Pasteur and his pupils on fermentation and contagious diseases, the question of microbes has become the order of the day.

In order to show our readers the importance of the study of the microbes, and the results that may be reached by following the scientific method created by Mr. Pasteur, it appears to us indispensable to give a summary of the history of these organisms. In the first place, what is a microbe? Although much employed, the word has not been well defined, and it would be easy to find several definitions of it. In its most general sense, the term microbe designates certain colorless algae belonging to the family Bacteriaceae, the principal forms of which are known under the name of Micrococcus. Bacterium, Bacillus. Vibrio, /Spirillum, etc.

In order to observe these different forms of Bacteriaceae it is only necessary to examine microscopically a drop of water in which organic matter has been macerated, when there will be seen Micrococci (Fig. 2, I.)looking like spherical granules, Bacteria in the form of very short rods, Bacilli (Fig. 2, V.), Vibriones (Fig. 2, IV.,) moving their straight or curved filaments, and Spirilli (Fig. 2, VI.), rolled up spirally. These varied forms are not absolutely constant, for it often happens in the course of its existence that a species assumes different shapes, so that it is difficult to take the form of these algae as a basis for classifying them, when all the phases of their development have not been studied.

The Bacteriaceae are reproduced with amazing rapidity. If the temperature is proper, a limpid liquid such as chicken or veal broth will, in a few hours, become turbid and contain millions of these organisms. Multiplication is effected through fission, that is to say, each globule or filament, after elongating, divides into two segments, each of which increases in its turn, to again divide into two parts, and so on (Fig. 2, I. b). But multiplication in this way only takes place when the bacteria are placed in a proper nutritive liquid; and it ceases when the liquid becomes impoverished and the conditions of life become difficult. It is at this moment that the formation of spores occurs—reproductive bodies that are destined to permit the algae to traverse, without perishing, those phases where life is impossible. The spores are small, brilliant bodies that form in the center or at the extremity of each articulation or globule of the bacterium (Fig. 2, II. l), and are set free through the breaking up of the joints. There are, therefore, two phases to be distinguished in the life of microbes—that of active life, during which they multiply with great rapidity, are most active, and cause sicknesses or fermentations, and that of retarded life, that is to say, the state, of resting spores in which the organisms are inactive and consequently harmless. It is curious to find that the resistance to the two causes of destruction is very different in the two cases.

In the state of active life the bacterides are killed by a temperature of from 70 to 80 degrees, while the spores require the application of a temperature of from 100 to 120 degrees to kill them. Oxygen of a high pressure, which is, as well known from Bert's researches, a poison for living beings, kills many bacteria in the state of active life, but has no influence upon their spores.

In a state of active life the bacteriae are interesting to study. The absence of green matter prevents them from feeding upon mineral matter, and they are therefore obliged to subsist upon organic matter, just as do plants that are destitute of chlorophyl (such as fungi, broomrapes, etc.). This is why they are only met with in living beings or upon organic substances. The majority of these algae develop very well in the air, and then consume oxygen and exhale carbonic acid, like all living beings. If the supply of air be cut off, they resist asphyxia and take the oxygen that they require from the compounds that surround them. The result is a complete and rapid decomposition of the organic materials, or a fermentation. Finally, there are even certain species that die in the presence of free oxygen, and that can only live by protecting themselves from contact with this gas through a sort of jelly. These are ferments, such as Bacillus amylobacter, or butyric ferment, and B. septicus, or ferment of the putrefaction of nitrogenized substances.



These properties explain the regular distribution of bacteria in liquids exposed to the air. Thus, in water in which plants have been macerated the surface of the liquid is occupied by Bacillus subtilis. which has need of free oxygen in order to live, while in the bulk of the liquid, in the vegetable tissues, we find other bacteria, notably B. amylobacter, which lives very well by consuming oxygen in a state of combination. Bacteria, then, can only live in organic matters, now in the presence and now in the absence of air.

What we have just said allows us to understand the process of cultivating these organisms. When it is desired to obtain these algae, we must take organic matters or infusions of such. These liquids or substances are heated to at least 120 deg. in order to kill the germs that they may contain, and this is called "sterilizing." In this sterilized liquid are then sown the bacteria that it is desired to study, and by this means they can be obtained in a state of very great purity.

The Bacteriaceae are very numerous. Among them we must distinguish those that live in inert organic matters, alimentary substances, or debris of living beings, and which cause chemical decompositions called fermentations. Such are Mycoderma aceti, which converts the alcohol of fermented beverages into vinegar; Micrococcus ureae, which converts the urea of urine into carbonate of ammonia, and Micrococcus nitrificans, which converts nitrogenized matters into intrates, etc. Some, that live upon food products, produce therein special coloring matters; such are the bacterium of blue milk, and Micrococcus prodigiosus (Fig. 2, I.), a red alga that lives upon bread and forms those bloody spots that were formerly considered by the superstitious as the precursors of great calamities.



Another group of bacteria has assumed considerable importance in pathology, and that is the one whose species inhabit the tissues of living animals, and cause more or less serious alterations therein, and often death. Most contagious diseases and epidemics are due to algae of this latter group. To cite only those whose origin is well known, we may mention the bacterium that causes charbon, the micrococcus of chicken cholera, and that of hog measles.

It will be seen from this sketch how important the study of these organisms is to man, since be must defend his body against their invasions or utilize them for bringing about useful chemical modifications in organic matters.

Our Servants.—We scarcely know what services microbes may render us, yet the study of them, which has but recently been begun, has already shown, through the remarkable labors of Messrs. Pasteur, Schloesing and Muntz, Van Tieghem, Cohn, Koch, etc., the importance of these organisms in nature. All of us have seen wine when exposed to air gradually sour, and become converted into vinegar, and we know that in this case the surface of the liquid is covered with white pellicles called "mother of vinegar." These pellicles are made up of myriads of globules of Mycoderma aceti. This mycoderm is the principal agent in the acidification of wine, and it is it that takes oxygen from the air and fixes it in the alcohol to convert it into vinegar. If the pellicle that forms becomes immersed in the liquid, the wine will cease to sour.

The vinegar manufacturers of Orleans did not suspect the role of the mother of vinegar in the production of this article when they were employing empirical processes that had been established by practice. The vats were often infested by small worms ("vinegar eals") which disputed with the mycoderma for the oxygen, killed it through submersion, and caused the loss of batches that had been under troublesome preparation for months. Since Mr. Pasteur's researches, the Mycoderma aceti has been sown directly in the slightly acidified wine, and an excellent quality of vinegar has thus been obtained, with no fear of an occurrence of the disasters that accompanied the old process.

Another example will show us the microbes in activity in the earth. Let us take a pinch of vegetable mould, water it with ammonia compounds, and analyze it, and we shall find nitrates therein. Whence came these nitrates? They came from the oxidation of the ammonia compounds brought about by moistening, since the nitrogen of the air does not seem to combine under normal conditions with the surrounding oxygen. This oxidation of ammonia compounds is brought about, as has been shown by Messrs. Schloesing and Muntz, by a special ferment, the Micrococcus nitrificans, that belongs to the group of Bacteriacae. In fact, the vapors of chloroform, which anesthetize plants, also prevent nitrification, since they anaesthetize the nitric ferment. So, too, when we heat vegetable humus to 100 deg., nitrification is arrested, because the ferment is killed. Finally, we may sow the nitric ferment in calcined earth and cause nitrification to occur therein as surely as we can bring about a fermentation in wine by sowing Mycoderma aceti in it.

The nitric ferment exists in all soils and in all latitudes, and converts the ammoniacal matters carried along by the rain into nitrates of a form most assimilable by plants. It therefore constitutes one of the important elements for fertilizing the earth.

Finally, we must refer to the numerous bacteria that occasion putrefaction in vegetable or animal organisms. These microbes, which float in the air, fall upon dead animals or plants, develop thereon, and convert into mineral matters the immediate principles of which the tissues are composed, and thus continually restore to the air and soil the elements necessary for the formation of new organic substances. Thus, Bacillus amylobacter (Fig. 2, II.), as Mr. Van Tieghem has shown, subsists upon the hydrocarbons contained in plants, and disorganizes vegetable tissues in disengaging hydrogen, carbonic acid, and vegetable acids. Bacterium roseopersicina forms, in pools, rosy or red pellicles that cover vegetable debris and disengage gases of an offensive odor. This bacterium develops in so great quantity upon low shores covered with fragments of algae as to sometimes spread over an extent of several kilometers. These microbes, like many others, continuously mineralize organic substances, and thus exhibit themselves as the indispensable agents of the movement of the matter that incessantly circulates from the mineral to the organic world, and vice versa.—Science et Nature.

* * * * *

Palms sprouted from seeds kept warm by contact of the vessel with the water boiler of a kitchen range are grown by a man in New York.

* * * * *



EPITAPHIUM CHYMICUM.

The following epitaph was written by a Dr. Godfrey, who died in Dublin in 1755:

Here lieth, to digest macerate, and amalgamate into clay, In Batneo Arenae, Stratum super Stratum The Residuum, Terra damnata and Caput Mortuum, Of BOYLE GODFREY, Chymist and M.D. A man who in this Earthly Laboratory pursued various Processes to obtain Arcanum Vitae, Or the Secret to Live; Also Aurum Vitae, or the art of getting rather than making gold. Alchymist-like, all his Labour and Projection, as Mercury in the Fire, Evaporated in Fume when he Dissolved to his first principles. He departed as poor as the last drops of an Alembic; for Riches are not poured on the Adepts of this world. Though fond of News, he carefully avoided the Fermentation, Effervescence, and Decrepitation of this life. Full seventy years his Exalted Essence was hermetically sealed in its Terrene Matrass; but the Radical Moisture being exhausted, the Elixir Vitae spent, And exsiccate to a Cuticle, he could not suspend longer in his Vehicle, but precipitated Gradatim, per Campanam, to his original dust. May that light, brighter than Bolognian Phosphorus, Preserve him from the Athanor, Empyreuma, and Reverberatory Furnace of the other world, Depurate him from the Faeces and Scoria of this, Highly Rectify and Volatilize, his aethereal spirit, Bring it over the Helm of the Retort of this Globe, place in a proper Recipient or Crystalline orb, Among the elect of the Flowers of Benjamin; never to be saturated till the General Resuscitation, Deflagration, Calcination, and Sublimation of all things.

* * * * *



A NEW STOVE CLIMBER.

(Ipomaea thomsoniana.)

The first time we saw flowers of this beautiful new climbing plant (about a year ago) we thought that it was a white-flowered variety of the favorite old Ipomaea Horsfalliae, as it so nearly resembles it. It has, however, been proved to be a distinct new species, and Dr. Masters has named it in compliment to Mr. Thomson of Edinburgh. It differs from I. Horsfalliae in having the leaflets in sets of threes instead of fives, and, moreover, they are quite entire. The flowers, too, are quite double the size of those of Horsfalliae, but are produced in clusters in much the same way; they are snow-white. This Ipomaea is indeed a welcome addition to the list of stove-climbing plants, and will undoubtedly become as popular as I. Horsfalliae, which may be found in almost every stove. It is of easy culture and of rapid growth, and it is to be hoped that it is as continuous in flowering as Horsfalliae. It is among the new plants of the year now being distributed by Mr. B.S. Williams, of the Victoria Nurseries, Upper Holloway.—The Garden.



* * * * *



HISTORY OF WHEAT.

Isis was supposed to have introduced wheat into Egypt, Demeter into Greece, and the Emperor Chin-Wong into China, about 3000 B.C. In Europe it was cultivated before the period of history, as samples have been recovered from the lacustrine dwellings of Switzerland.

The first wheat raised in the "New World" was sown by the Spaniards on the island of Isabella, in January, 1494, and on March the 30th the ears were gathered. The foundation of the wheat harvest of Mexico is said to have been three or four grains carefully cultivated in 1530, and preserved by a slave of Cortez. The first crop of Quito was raised by a Franciscan monk in front of the convent. Garcilasso de la Vega affirms that in Peru, up to 1658, wheaten bread had not been sold in Cusco. Wheat was first sown by Goshnold Cuttyhunk, on one of the Elizabeth Islands in Buzzard's Bay, off Massachusetts, in 1602, when he first explored the coast. In 1604, on the island of St. Croix, near Calais, Me., the Sieur de Monts had some wheat sown which flourished finely. In 1611 the first wheat appears to have been sown in Virginia. In 1626, samples of wheat grown in the Dutch Colony at New Netherlands were shown in Holland. It is probable that wheat was sown in the Plymouth Colony prior to 1629, though we find no record of it, and in 1629 wheat was ordered from England to be used as seed. In 1718 wheat was introduced into the valley of the Mississippi by the "Western Company." In 1799 it was among the cultivated crops of the Pimos Indians of the Gila River, New Mexico.

* * * * *



DETERMINATION OF STARCH.

According to Bunzener and Fries (Zeitschrift fur das gesammte Brauwesen), a thick, sirupy starch paste prepared with a boiling one per cent solution of salicylic acid is only very slowly saccharified, and on cooling deposits crystalline plates of starch. For the determination of starch in barley the finely-ground sample is boiled for three-quarters of an hour with about thirty times its weight of a one per cent solution of salicylic acid, the resulting colorless opalescent liquid filtered with the aid of suction, and the starch therein inverted by means of hydrochloric acid. The dextrose formed is estimated by Fehling's solution. The results are one to two per cent higher than when the starch is brought into solution by water at 135 deg. C.

* * * * *

A catalogue, containing brief notices of many important scientific papers heretofore published in the SUPPLEMENT, may be had gratis at this office.

* * * * *



THE SCIENTIFIC AMERICAN SUPPLEMENT.

PUBLISHED WEEKLY.

TERMS OF SUBSCRIPTION, $5 A YEAR.

Sent by mail, postage prepaid, to subscribers in any part of the United States or Canada. Six dollars a year, sent, prepaid, to any foreign country.

All the back numbers of THE SUPPLEMENT, from the commencement, January 1, 1876, can be had. Price, 10 cents each.

All the back volumes of THE SUPPLEMENT can likewise be supplied. Two volumes are issued yearly. Price of each volume, $2.50, stitched in paper, or $3.50, bound in stiff covers.

COMBINED RATES—One copy of SCIENTIFIC AMERICAN and one copy of SCIENTIFIC AMERICAN SUPPLEMENT, one year, postpaid, $7.00.

A liberal discount to booksellers, news agents, and canvassers.

MUNN & CO., PUBLISHERS,

361 BROADWAY, NEW YORK, N. Y.

* * * * *



PATENTS.

In connection with the SCIENTIFIC AMERICAN, Messrs. MUNN & Co. are Solicitors of American and Foreign Patents, have had 39 years' experience, and now have the largest establishment in the world. Patents are obtained on the best terms.

A special notice is made in the SCIENTIFIC AMERICAN of all Inventions patented through this Agency, with the name and residence of the Patentee. By the immense circulation thus given, public attention is directed to the merits of the new patent, and sales or introduction often easily effected.

Any person who has made a new discovery or invention can ascertain, free of charge, whether a patent can probably be obtained, by writing to MUNN & Co.

We also send free our Hand Book about the Patent Laws, Patents, Caveats. Trade Marks, their costs, and how procured. Address

MUNN & CO., 361 BROADWAY, NEW YORK.

Branch Office, cor. F and 7th Sts., Washington, D. C.

THE END