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HYDRAZOIC ACID: A NEW FORM OF APPARATUS FOR
ITS PREPARATION; ITS PHYSIOLOGICAL ACTION.
BY CYRIL G. HOPKINS, SOUTH DAKOTA AGRICULTURAL COLLEGE,
BROOKINGS, SOUTH DAKOTA.

MOST of the text-books on the subject of chemistry in use at the present time still recognize but one compound of hydrogen and nitrogen, viz., ammonia. There are, however, now known to science, several compounds of these two elements. Of these the most important are ammonia, NH,; hydrazoic acid, HN,; and hydrazine, NH. There is a remarkable difference in the properties of the first two substances. Ammonia, the volatile alkali, has very strong basic properties, uniting directly with acids to form the ammonium salts. Only with the strongest basic elements does it act like an acid, forming sodium amide, NaNH,, with sodium, and potassium amide, KNH,, with potassium.

Hydrazoic acid, on the contrary, is a comparatively strong acid. Being a binary compound of hydrogen and nitrogen, it might well be called hydronitric acid, after the analogy of hydrochloric acid, hydrobromic acid, etc. Its structural formula is represented thus::

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Thus we have at least six compounds of the elements hydrogen and nitrogen, their general formulas being :

NH,, NgH, N,H,, NgHs, NgHs, and HN. Heretofore hydrazoic acid and its derivatives have been made only by reactions' of organic chemistry; but within the past few months a method has been devised by Wislecenus by which the acid is made entirely from inorganic substances. This is done by first treating molten metallic sodium (or potassium) with dry ammonia gas, and then treating the sodium amide thus formed

1 Berichte der deutsch. Chem. Gesellschaft (Curtius), xxiii., 3023; xxiv., 3845. Ibid (Noeting and Grandmongin), xxiv., 2546.

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with dry nitrous oxide. The sodium salt of hydrazoic acid is thus formed; and, by treating this with dilute sulphuric acid, the hydrazoic acid itself is liberated, and may then be distilled off with water, thus giving a dilute aqueous solution.

Wislecenus performed the operation in a small porcelain boat within a glass tube. The porcelain is strongly attacked by the sodium compounds, and the yield of hydrazoic acid which Wislecenus obtained was nearly 50 per cent of the theoretical amount, and, besides, only a small quantity of the acid (about one-half a gramme) could be made at a time.

These objections to the apparatus used by Wislecenus induced the author to seek for a better form of apparatus with which to prepare the acid.

A cylindrical copper air-bath was selected, which was provided with two mica windows placed opposite each other, through which any operation that was carried on within the bath could be easily observed. The bath was about fifteen centimetres from top to bottom and of about an equal diameter. The cover was of heavy asbestos board. In the centre of this a large circular opening was made, through which a glass beaker of 750 cubic centimetres capacity was inserted into the bath until its rim rested upon the asbestos board, the bottom of the beaker not being allowed to touch the bottom of the bath. A small quantity of clean sand was placed in the bottom of the beaker, and upon this a small iron sand-bath, hemispherical in shape, and having a capacity of 100 cubic centimetres. The mouth of the beaker was closed with a large flat cork, provided with three holes. Through the central hole passes a glass tube which reaches a little way into the iron dish, and through which the gases are conducted into the apparatus. The second hole carries a short exit tube, and the third a thermometer.

Neither the metallic sodium nor the compounds formed have any action upon the iron dish, and the reactions which take place in the dish can be readily observed through the mica windows of the air-bath and the glass beaker.

The ammonia gas was obtained by gently heating on a waterbath a flask containing strong ammonia water, and the nitrous oxide by the decomposition of ammonium nitrate by heat. The gases were dried as directed by Wislecenus, by passing them over soda-lime and solid potassium hydroxide.

To perform the operation 25 grammes of metallic sodium were placed in the iron dish, the temperature of the bath raised to 300° - 360° C., and dry ammonia gas conducted in and delivered just above the surface of the molten sodium. The specific gravity of sodium being less than that of the amide formed, the metal floats on the surface until the action is finished. The reaction is represented by the equation:—

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When the globules of sodium had all disappeared, the nitrous oxide was substituted for the ammonia, and the temperature of the bath lowered to 230° – 250° C. Two reactions now take place. The two atoms of hydrogen in the sodium amide are replaced by the bivalent group, N,, contained in the nitrous oxide, the hydrogen and oxygen uniting to form water. This then reacts with a second molecule of sodium amide, forming sodium hydroxide and ammonia :

NaNH, + N,O =(NaNN, = NaNg) + H,O, and
NaNH, +H,O = NaOH + NH

The sodium compounds have a strong tendency to creep over the edge of the iron dish as fast as they are formed; but they only fall upon the sand in the bottom of the beaker, from which they are readily dissolved out by water.

When the odor of ammonia ceases to be given off, the reaction is complete. The apparatus was allowed to cool, the mixture of sodium hydroxide and the sodium salt of hydrazoic acid was dis

solved in 500 cubic centimetres of water, and then dilute sulphuric acid added till the hydrazoic acid was liberated. The solution was then distilled till the distillate ceased to give a precipitate with silver nitrate.

The distillate was then diluted to a definite volume and its strength determined by titration with standard ammonia solution. The yield of the acid was 87 per cent of the theoretical, 500 cubic centimetres of nearly 4 per cent solution being obtained.

A part of the acid solution was neutralized with potassium carbonate, and evaporated to crystallization. Beautiful, tabular, transparent crystals of the potassium salt, KN,, were formed.

The salts of hydrazoic acid, excepting the salts of the alkali metals and the metals of the alkaline earths, are explosive. In some respects the acid resembles hydrochloric acid. With soluble silver salts a white precipitate, AgN,, is formed. Lead acts similarly. These salts explode very violently when heated.

The most remarkable property of hydrazoic acid and its soluble salts is their physiological action. In this respect they resemble the nitrite of amyl, CH11NO,, having a marked influence upon the action of the heart. The author found by experiment that one-tenth of a grain of the potassium salt, KN,, dissolved upon the tongue (the resulting solution not being swallowed, but ejected from the mouth) was sufficient to increase the pulse from 96 beats per minute to 153. This required only five minutes' time after the dose was taken. This rate of heart-beat.is not sustained, however. A sudden and rapid reduction takes place, and ten minutes after the dose was taken the heart was giving 60 feeble beats per minute, making a total variation of 97 beats per minute. Considering the fact that this effect was produced by the small quantity of the substance which was absorbed by the mucous membrane of the tongue, this property is certainly remarkable. The vapors of the hydrazoic acid produce similar effects when inhaled.

The laboratory work reported in this article was performed in the chemical laboratory of Cornell University; and the author wishes to acknowledge that the success of the work was largely due to the aid and direction given by Dr. W. R. Orndorff. Thanks are also due him for his kindness in reading and correcting the manuscript.

ON PROTOPTERUS ANNECTENS.

BY DR. R. W. SHUFELDT, WASHINGTON, D.C.

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THERE has been very recently published in the Transactions of the Royal Irish Academy (Vol. XXX., Part III., pp 109-230, Plates vii. to xvii) the long-delayed work of Professor W. N. Parker of the University College, at Cardiff, Wales, On the Anatomy and Physiology of Protopterus annectens." Through the courtesy of its author, a reprint of that most valuable quarto is now before me, and it is my wish to write a brief notice here in regard to it. The elaborate manner in which the Transactions of the Academy are published is too well know to require remark, but in the present instance it is impossible to pass this work without a word upon the truly superb plates that illustrate it. These, some ten in number, were chromo-lithographed by Professor Parker's younger brother, M. P. Parker, and printed by West, Newman. They present us with much of the anatomy and histology of Protopterus, and are throughout perfect masterpieces of the kind, and of the very highest order of merit.

As is well known, this genus formerly was written Lepidosiren, the South American species being L. paradoxu, and the African one L. annectens,' and among the first to pay any attention to it, of a reliable nature, was Sir Richard Owen, who, in 1839-1841, Dr. Günther classifies them as follows:Suborder III.

ORDER II.-Ganoldel {Dipnol.

Families. 1. Sirenida 2. Ctenodod!pteridæ 3 Phancropleurida (

Genera. (Lepid siren, incl. Protopterus Ceratodus. Two extinct genera, Dipterus and Hellodus. Extinct Phaucropleuron.

And he remarks that "Two species are known, L. paradoxa, from the system of the river Amazon, and L. (Prot p'erus) annectens, which abounds in many localities of the west coast of Africa, is spread over the whole of tropical Africa, and in many districts of the central parts forms a regular article of diet."

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published his Description of Lepidosiren annectens" in the Transactions of the Linnæan Society of London (Vol XVIII.), since which time naturalists have never ceased to furnish various accounts of the biology of this extremely important form, but usually based, as Professor Parker remarks, upon badly preserved material. Our present author was far more fortunate as he had perfectly fresh specimens to work upon. Of these he has said in his "Introduction," that "All my material, with the exception of two specimens, purchased last autumn, were placed at my disposal by Professor Wiedersheim. These were received alive direct from the neighborhood of the Gambia, and to Dr. J. Beard is due the credit of having arranged for their transport. While in the torpid condition about one hundred specimens had been dug out, each surrounded by a clod of earth,' and the clods were then packed together in open crates. In this manner they travelled without harm, nearly all of them being alive and in a healthy condition on their arrival in Freiburg. On being removed from the clods, they were, by the kind permission of Professor Hildebrandt, placed in a large wire cage, sunk beneath the water in a basin used for the culture of water plants in one of the hot-houses of the Botanical Gardens, in which a constant temperature of 22.5° C. was maintained." . . . Protopterus lives probably to a great age, and this supposition is supported by the somewhat incredible statement of the natives mentioned by Stuhlmann, that some specimens reach a length of six feet. From the observations of Hyrtl and Bischoff, it appears that Lepidosiren also attains a large size, reaching, at any rate, three feet in length" (p 112).

6.

It was found that Protopterus grows very rapidly, has great vitality, and, although able to sustain fasts, is exceedingly voracious, devouring all the abundant snails, earth-worms, and small fish given them, and then killing and eating each other, making it difficult in the extreme to preserve the specimens.

Protopterus is most active at night, and appears to keep mostly to the shallow water, where they move deliberately about on the bottom, alternately using the peculiar limbs of either side, though their movements do not seem to be guided by any strict regularity. "Gray has compared these movements with those of a Triton, and several other observers have noticed them. The powerful tail forms a most efficient organ for swimming rapidly through the water."

"It is well known that Protopterus comes to the surface to breathe at short intervals, and thus it is evident that the lungs perform an important, if not the chief, part in respiration during the active life of the animal. The air passes out again through the opercular aperture, and the movements of the operculum itself indicate the fact that bronchial as well as pulmonary respiration takes place."

Externally, the sexes present no characters whatever distinguishing them apart, and even in immature specimens it is difficult to tell ovary from testis.

In the present brief notice it will be impossible for us to even abstract the positive advances Professor Parker has made for us in our knowledge of both the anatomy and physiology of this instructive Dipnoan. He sums up handsomely on page 213, under his "General Abstract, Summary of Chief Resu'ts, and Conclusions."

His researches convince him that, although many points of resemblance exist between Protopterus and certain Elasmobranchs and Ganoids on the one hand, and on the other to some of the lower Amphibians, it exhibits numerous distinctive characters of its own, both primitive and specialized, and so, together with Lepidosiren and Ceratodus, must be placed at a great distance from either class. Further, he believes that the Dipnoi, as a group, should not be retained among the fishes, still less among the Amphibia.

To those less familiar with the habits of this extraordinary fish, I would say that the species averages about four feet in length, and is an inhabitant of the Gambia River in Africa. They bury themselves in the mud during the dry season, making a kind of nest in which they pass a period of torpidity. Here they may remain for the best part of the year, but on the return of the wet season resume again their aquatic mode of lite.

In 1889, it will be remembered, Stuhlmann also gave an interesting account of Protopterus, published in German. (Berlin.)

Highly specialized in some respects, in both Protopterus and Lepidosiren, this specialization is largely due to a change of habit, and that, undoudtedly, these two types are, genericly, very distinct.

In conclusion, I may simply add that this classical work will, in the future, prove to be one of the very greatest value to all students of the morphology of the Amphibia and of Pisces, as it will be indispensible to the general biologist.

OBSERVATIONS ON A CYCLONE NEAR WILLIAMSTOWN, KANSAS.

BY E. H. S. BAILEY, UNIVERSITY OF KANSAS, LAWRENCE, KAN. A SEVERE and fatal cyclone visited a small area of country in the Kaw valley, in Jefferson County, on June 21, at about six o'clock in the evening, and the peculiar topography of the country gave an opportunity to make some observations that may be of scientific interest. The valley at this point is about two miles in width, the river running nearly east. On the south side it is bounded by bluffs about a hundred feet in height, and on the north side there is a strip of level meadow, something over a mile in width, before one reaches the bluffs, which are of about the same height as those on the south side.

The general trend of the broad valley is east, but at a point a mile or so beyond where the cyclone lifted the river runs toward the southeast for perhaps a mile. On the particular afternoon in question the weather had been extremely hot and sultry, the mercury ranging between 90° and 95° F. The weather had been warm and dry, with only one local shower for about two weeks. About two hours before the cyclone burst upon the valley there was a gathering of clouds in the northwest, with thunder and lightning. A short time before the storm burst an ominous stillness was noted, and a sudden darkening of the sky. During the heaviest of the storm a peculiar green tint of the sky was noticed in the locality.

As the storm came from the west, it seemed to settle near the ground at the base of the bluff, and, wherever the bluff was not broken by lateral valleys, its path was about one-half on the side of the hill and the other half on the sloping meadow to the south.

Wherever the cyclone crossed the course of lateral ravines, even if they were quite narrow, it dipped down into them and destroyed trees and buildings. It was not swerved from its general eastward course even at one point where a broader valley joined that of the Kaw. At this point, as the country was heavily timbered, there was a special opportunity to observe the action of the wind. Elm and walnut trees. two or three feet in diameter, were either torn up by the roots, laid prostrate, or twisted off fifteen or twenty feet from the ground. Here the track of the cyclone, where it did appreciable damage, was a little less than 600 yards in width. There were, occasionally, wrecked chimneys and slightly injured roofs on the outer edges of this path. All along the course of the storm the debris was deposited in the peculiar way that is characteristic of these furious whirlwinds. The material north of the centre of the track was deposited in lines from northwest to southeast, and that on the south side of the centre in lines running from southwest to northeast. In the centre of the track there was a tendency to distribute the material in an east and west direction. A line of telephone poles on the south side were laid in parallel lines, thus, /////. Fields of grass and wheat were beaten to the ground and the stalks laid in the directions above noted: W. E. The wires of

the telephone line and of the barb-wire fence were lifted into the tree-tops about fifty feet north of their original position. There was a little debris deposited on the west side of some of the buildings demolished, but most of it was carried along the track and thoroughly pulverized. Strong, new farm wagons were wrenched to pieces, and the spokes were even broken off near the hub, before they were deposited half a mile away.

The terrible force of the wind could be seen in the beheading of the wheat, the uncovering of potatoes in the hills, the transportation of grave-stones 300 yards, and the picking of all the feathers from the chickens

One of the most interesting effects that was noticed was upon

the trees that were left standing or laid prostrate and bereft of every vestige of foliage and of nearly all the bark. All the wood on the west side of these trees, often being exposed by having the bark torn off, was roughened as if by a sand blast; while that on the east side was smooth. This roughness was uniform, showing that it was not produced by occasional missiles hurled through the air. This roughening, if not produced by the actual friction of the air, must have been produced by the sand and gravel in the air, or by the rain that beat against the surface.

Some who witnessed the storm saw the clouds of dust that accompanied the wind, so the sand-blast theory is no doubt the correct explanation.

The most serious work of destruction was accomplished just before the cyclone lifted. Here the valley broadened out towards the north, and the bluff for a distance of a mile or more disappeared. With one last sweeping blow the storm lifted, and the only other evidence of its work was a partially demolished barn. Just at the point where the intensity seemed concentrated, the path was much narrower than farther west. The strip of land devastated was about five miles in length. From the manner in which it followed the base of the bluff, one would infer that bad it not been for this obstruction the storm would have passed off towards the northeast instead of pursuing, as it did, a direction a little south of east.

NOTES ON THE COPEPODA OF WISCONSIN.

BY C. DWIGHT MARSH, RIPON, WISCONSIN.

In the waters of Wisconsin and in the adjacent lakes are found the following twenty-one species of free-swimming copepods: Diaptomus sanguineus, Forbes; D. leptopus, Forbes; D. pallidus. Herrick; D. sicilis, Forbes; D. ashlandi sp. nov; D. minutus, Lillj.; D. oregonensis, Lillj.; Epischura lacustris, Forbes; Limnocalanus macrurus, Sars; Cyclops americanus, sp. nov.; C. brevispinosus, Herrick; C. pulchellus. Koch; C. navus, Herrick; C. parcus, Herrick; C. leucarti, Sars; C. signatus, Koch; C. modestus, Herrick; C. fluviatilis, Herrick: C. serrulatus, Fischer; C. phaleratus, Koch; C fimbriatus. Fischer.

Although two of these, D. ashlandi and C. americanus, are new species, it is not probable that they are peculiar to the Wisconsin fauna. The copepods of America have thus far received very little attention, the only important publications on the subject being by three men, Professor Cragin, Professor Herrick and Professor Forbes. If more were known of our copepods it is probable that it would be found that there are few local differences in the fauna of our northern States. The copepods are readily transported from one body of water to another and, without change of structure, seem to endure great changes in their environment In fact, half of our species of cyclops are not only widely distributed in America, but are identical with those of Europe. Those that may be considered distinctly American are closely allied to well-known European forms.

C. leucarti is found in nearly all parts of the world where collections have been made and, so far as can be inferred from the published descriptions, varies but little, even in the minute details of its structure.

C. americanus closely resembles C. viridis, and is probably the species which has by other American authors been identified with viridis. Although there seems to be good reason for separating it from the European species, the similarity of the two forms is so great that it is only by a close examination that the structural differences become apparent.

It is very possible that C. brevispinosus should be considered a pelagic variety of C. americanus, thus reducing by one the number of species peculiar to America. There is some reason, too, for supposing that C. navus is not specifically distinct from C. pulchellus.

C. pulchellus is the common pelagic form of the Great Lakes. Although found in smaller lakes, it is more commonly replaced by C. brevispinosus, which is a species of wide distribution. C. navus is found only in stagnant pools.

The most common of all our species is C. serrulatus. Rarely is a collection without this form, which seems to adapt itself easily to very different surroundings. It has, however, wide

limits of variation, and it is, perhaps, due to this fact that it is so universally distributed. The littoral and pelagic forms are so different that they have been considered specifically distinct. C. modestus is a rare form. Thus far it has been found in only a single locality in Wisconsin.

None of the American species of Diuptomus is identical with those of Europe, although in some cases the relationship is very close.

D. sicilis is the common pelagic form of the Great Lakes, but occurs also in smaller bodies of water. D. ashlandi has been found only in the Great Lakes.

The most common species in the smaller lakes is D. oregonensis. This was described by Lilljeborg from specimens collected in Oregon, and probably is common through our northern States. D. minutus is common in Newfoundland, Greenland and Iceland. It occurs in some of the small lakes in northern Wisconsin and in Green Lake. It is likely that it occurs quite generally through the northern part of North America, and possibly central Wisconsin is near its southern limit.

Especial interest attaches to the fauna of Green Lake. This is about seven miles long, with a maximum depth of nearly two hundred feet. While the pelagic fauna of the Great Lakes is quite distinct from that of the smaller lakes, we find in Green Lake both sets of fauna. D. sicilis and Limnocalanus macrurus I have not found outside the Great Lakes except in Green Lake. But besides these species the pelagic fauna of Green Lake includes C. brevispinosus and C. fluviatilis, which are the characteristic species of the smaller lakes.

A more detailed account of the Wisconsin copepoda will soon appear in the Transactions of the Wisconsin Academy.

THE HILLOCK AND MOUND FORMATIONS OF SOUTHERN CALIFORNIA.

BY DANIEL CLEVELAND, SAN DIEGO, CALIFORNIA.

SOME time ago, in an article upon the nest of the trap-door spider, which appeared in Science, I mentioned the low mounds in which these nests in many districts are so often located, as being in themselves an interesting formation. I now propose to offer an explanation of the origin of the formation.

Let me begin by saying that these mounds are not confined to this vicinity, for they extend throughout this State and elsewhere on this coast and in Texas; but they are more numerous and better defined here than elsewhere; they are, in fact, a characteristic of certain large areas of our territory. For this reason, among others, I believe this to be the best field for observing and investigating this remarkable formation.

Lying just back of the commercial portion of the city of San Diego there is a great mesa or table-land, which stretches away for a distance of from eight to ten miles to the valleys at the base of the Coast Range. It possesses a rich brown soil, holding in many places considerable aggregations of loose stones which have drifted down from the neighboring mountains and been ground into pebbles. Here for miles the surface is gently undulating, with low mounds lying as close together and as numerous, considering their size, as the ground will permit. These mounds are from one to three feet in height above their bases, and are from ten to thirty feet in diameter, separated by greatly varying areas which in their depressions in many places contain accumulations of cobble stones. An unscientific person seeing these plains for the first time might imagine that they had once been densely populated by large burrowing animals which had left these hillocks to mark their subterranean dwellings.

Several theories have been advanced to account for this formation. The most probable hypothesis is suggested by the nature of the soil and the peculiar vegetation of these plains. The soil itself is dry and hard for the six to eight months constituting the rainless season. During the time of heavy rains it is soft and mellow. During the time of drought it becomes almost as hard as stone.

Each mound, it is evident enough, marks the former home of a shrub or, as was almost always the case, of a cluster of shrubbery, to whose agency the mound in large degree owed its existThree shrubs-Rhus laurina, Nutt.; Simmondsia Califor

ence.

nia, Nutt.; and Isomeris arborea, Nutt.-are conspicuous among the large vegetation of these plains, and have been very important factors in the formation of these mounds. Of these plants Rhus laurina is the largest and is much more abundant than the other two. It is an interesting fact that these three shrubs are confined to this section of California, mostly to this county, and that they were all first collected at San Diego about 1840, and were named by the eccentric naturalist Thomas Nuttall. He established the genera Simmondsia and Isomeris. The habits of these plants peculiarly fit them for their office of mound builders. They grow in small compact groups. Many stems rise from the roots, which are large and spreading. The foliage of Rhus and Simmondsia especially is dense and falls close to the ground.

Dust blown by the steady trade winds of the dry season is arrested by the shrub and accumulates with the fallen leaves at its base, making a steady accretion of material. In this way a mound gradually rises about the plant, in time covering the lower branches and in the case of the smaller shrubs - Simmondsia and Isomeris-nearly or quite enveloping the whole plant. This process of mound building can still be seen in isolated hillocks. An examination of the older mounds confirms this theory. In the lower portion of the mound the earth is compact and indurated, while the surface soil is a light loam mixed with decayed and decaying leaves. The mound is protected from washing by the rains at the summit by the overhanging branches and foliage, and at the base by a compact mass of roots. Outside of the foliage and roots the process of erosion goes on steadily, though slowly, during the rainy season, when this soil is peculiarly susceptible to the action of water, and the hollows between the mounds are then formed.

When in the course of time the plant dies from natural decay, from being smothered by the drift that environs it or from the fires that sometimes sweep over these plains, the mounds, being deprived of protection, are attacked by wind and rain and gradually worn down. The mounds are thus made shallower and broader at the base, until from this steady subsidence they sink down and flatten out almost to the general level of the plain.

The presence of living shrubs upon the more perfect mounds and of masses of roots well preserved or in process of decay in mounds in subsidence, where no large growing vegetation has been seen for many years, and in the oldest and flattest mounds the disappearance of all traces of shrubs and roots, confirm our theory of mound formation and subsidence.

What the shrubs I have named-Rhus, Simmondsia and Isomeris have effected in coöperation with the wind and rain in the formation of mounds in this section, has been accomplished elsewhere by other shrubs and trees. It is a familiar fact that upon the great prairies of Texas mats of timber are generally found upon the summit of hillocks, very much larger. of course, than the mounds of southern California, as those trees are larger than our shrubs.

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Two or three years ago the State of Oaxaca, in Mexico, established an Archæological Museum, and placed it in charge of the very competent and enthusiastic scientist, Dr. Nicolas Leon, of Michoacan, who had already won for himself a wide reputation as curator of the Museum at Morelia. Through some unfortunate political changes the modest appropriations awarded to both these institutions have been diverted into other channels. This is a matter of great regret to all who are interested in the preservation of the ancient monuments of Mexico and the further investigations into the numerous remains there found.

The State of Oaxaca especially has an archæological importance which attaches a unique value to the investigation of its remains. From the earliest days of which tradition records the echoes, it was the home of the Zapotecs, and the profoundest researches into the pre-Columbian origin of the Aztec and Mexican civilization point, not to the fabulous "Empire of the Toltecs," but to these Zapotecs as the tribe which first spread abroad

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