September 25, 1885.] 



SCIENCE, 



263 



dromeda. The relative positions are shown in the 

 adjoining cut. 



The ' lines ' at 18.6 and 19 appear, using the 

 broad slit, as bright knots. That at 17.5 as a long 

 line. The arrangement of the lines suggests certain 

 bright lines in the spectrum of y Casseopeiae and /? 

 Lyrae, and the settings agree with those made upon 

 the spectrum of the said stars. 



O. T. S. 

 Tale college observatory, 

 Sept 14. 



The Mexican axolotl and its susceptibility to 

 transformations. 



Marie von Chauvin's experiments with the axolotl, 

 as recounted in Science No. 130, under the above 

 title, interested me very much indeed, inasmuch as 

 they came upon me at a time when I was experi- 

 menting with upwards of two hundred of these ani- 

 mals by very similar methods. 



My present field of research is in north-western 

 New Mexico, and several forms of axolotls are to be 

 found in the region. Last June (1885) I visited, near 

 my present residence, on more occasions than one, a 

 small pond that contained large numbers of them. 

 This pond is nearly square, and its sides something 

 over a hundred feet in length. It is divided in two 

 nearly equal parts by an east and west embankment. 

 This embankment has a narrow trench cut through 

 it, so that when the rain fills the ponds they commu- 

 nicate with each other; but this is not the case when 

 the water is low. 



By the 1st of September each year these ponds 

 are usually dried up; while during the spring and 

 smnmer months, the south one has a mid-depth rang- 

 ing between three and six feet, and the north one 

 being considerably shallower. These depths vary 

 with the amount of rainfall, and other meteorologi- 

 cal conditions. 



As I say, there were great numbers of axolotls in 

 these ponds; and as far as I could see, and by the 

 very kind assistance of Professor Cope, these were 

 of two kinds: one very large one (20 cms ±) seemed 

 to be the larval form of Ablystoma mavortium; 

 another much smaller one (9 cms ±) proves to be A. 

 tigrinum. In addition to these, there are some me- 

 dium-sized ones that are very puzzling, and not yet 

 satisfactorily diagnosed. With but few exceptions, 

 the north division of the pond contained the small 

 ones; while in the other side lived all the large ones, 

 together with the great majority of the light-colored 

 and undetermined forms. 



The limits of this paper will not permit me to pre- 

 sent all the conditions of environment under which 

 these axolotls live, much less an account of the 

 many observations I made upon their habits as they 

 are to be seen in a state of nature. At different 

 times I captured as many of these creatures as I de- 

 sired, to carry on my experiments at home, the results 

 of w^hich I had the unusual opportunity of compar- 

 ing with those changes undergone by these reptiles 

 while existing in their natural element. 



It is my sole aim in this paper to briefly present the 

 results of some of these experiments, so far as they 

 have gone, and compare them with those arrived at 

 by Miss von Chauvin, as set forth in Science. 



My observations confirm those of this talented 

 authoress, in that, — 



1. Axolotls are more readily converted into Am- 

 blystomas if kept in water containing but little air, 

 and vice versa. 



2. If transformation is forced up to a certain point 



in development, the reptile arrives at the higher form 

 without any further interference. 



3. Axolotls live in the water with apparent corn- 

 fort a considerable and varying length of time after 

 their gills have been absorbed. 



4. After the metamorphosis is completed, their 

 power to return to the water again to live, seems to 

 depend upon the moult, and whether they have lived 

 in moist or dry places since the metamorphosis. 



5. By varying the conditions under which these 

 animals live, we can at our pleasure retard or accel- 

 erate their development to the higher stages. 



6. Young axolotls are more easily transformed 

 than the older specimens, but this rule also depends 

 largely upon the conditions under which these ani- 

 mals live. 



There is another very important factor that enters 

 into this metamorphosis, that, so far as the account 

 in Science goes, is not touched upon; and that is, the 

 question of their diet during the experiments. Axo- 

 lotls are very voracious creatures, and eminently 

 carnivorous. They are very fond of raw meat; 

 and, upon the slightest provocation, they will feed 

 upon each other. So I have found, during the 

 course of my experiments, that, — 



7. The metamorphosis is hastened by regularly 

 supplying the animals with plenty of proper food. 

 And what is still more interesting, when they are 

 thus treated, it markedly affects the appearance of 

 the transformed Amblystoma. 



8. If, during the process of forcing the transfor- 

 mation of axolotls, the animals are regularly supplied 

 with the requisite amount of fresh meat, \he trans- 

 formed Amblystomas are very much larger and 

 stronger than those which are transformed without 

 having received any food. In the case of A. tigri- 

 num, those that received food, the transformed ani- 

 mal would hardly have been recognized as the same 

 species: they were not only larger, but of a very 

 deep, muddy, black color, without spots; while the 

 others were mottled with bright yellow, and a pale 

 brown. 



9. The depth of the water has a w^onderful influ- 

 ence upon the metamorphosis; and the fact is well 

 known, that, the deeper the water in which the 

 axolotls live, the slower their transformation. 



Temperature is another important factor in the 

 change, and its moderate increase seems to hasten 

 the transformation. 



Now, the most interesting part of all is to watch 

 the operation of these laws, that I have given, in 

 nature, and the manner in which the metamor- 

 phosis of axolotls is there effected. 



It would, indeed, be hard to find anywhere a more 

 perfect and beautiful example illustrating the ex- 

 tremely sensitive balance that may exist between the 

 surrounding conditions on the one hand, and their 

 effect upon an animal organism on the other. This 

 year, for instance, the very pond that I have alluded 

 to above, gradually dried up; the north half of it 

 entirely. This took a number of weeks ; but during 

 that time all the modifications of which the metamor- 

 phoses of axolotls are subject to, or capable of, were, 

 so far as their necessity goes, most lucidly demon- 

 strated. A shallow corner in this pond would, after 

 a torrid day or two, dry up; whereupon all the axo- 

 lotls that happened to be caught within its limits, 

 would be found, perhaps several hundred of them, 

 under the debris, rapidly assuming the Amblystoma 

 form. Numbers of the same generation, however, 

 in the deeper parts, would be unaffected by the change 

 of environment so suddenly precipitated upon their 

 brethren. If the drying-up continued, these trans- 



