352 ON CHANGE OF MEXICAN AXOLOTL TO AN AMBLYSTOMA. 



same experiment was made repeatedly aud was every time attended by 

 the same result; from which it may well be concluded that through the 

 exercise of too energetic constraint with a view to hasten the process of 

 transformation a stoppage may be brought about, aud death, indeed, by 

 continued constraint. 



"Of Axolotl V. it remains to be stated that he crept out of the water, not 

 like all the others at the first molt, but at the time of the fourth. 



"All these are to-day alive, healthily and strongly developed, so that^ 

 as regards their nourishment, nothing would stand in the way of their 

 propagation. The largest of the first four has a length of 15 centime- 

 tres. Axolotl V. measures 12 centimetres. 



"From what I have said must be established the correctness of the 

 view suggested in the beginning: most Axolotl larvre, if not all, com- 

 plete their metamorphose, if, in the first place, they come out of the 

 egg healthy and are properly fed, and, in the second place, meet with 

 arrangements which force them to change from breathing under water 

 to breathing above the water. It will be understood that this compul- 

 sion may only be exerted quite gradually, and in a way which does not 

 draw too much upon the animal's vital force. 



" Freiburg, Breisgau, July, 1875. 



"MAEIE V. CHAUVIN." 



I remark upon the above records, that in all five cases the change 

 v/as a complete one, not to be confounded with that which all the Axolotls 

 confined in small gloss vessels undergo more or less ; namely, . there 

 are frequently variations which seem to advance toward the Amblystoma 

 form without reaching it. In the five full-grown Axolotls which I possess 

 at this very time, and of which two at least are four years old, the gills 

 are all very much shriveled up, but tail and crest are unchanged. But 

 the crest may also disappear and the tail grow smaller without changing 

 to the Amblystoma, as shall be shown further on. As regards the time 

 used for the transformation, in Axolotls I. to V. it took 12 to 14 days. 

 Four days of that bring us to the first change, during which the animal 

 still remains in the water; the rest of the time is given to the comple- 

 tion of the change. Dumeril gives the time of the transformation at 16 

 days. 



From the experiments communicated the following seems to me espe- 

 cially noteworthy : The five Axolotl larvcv, which alone can come into the 

 account, since the others died early, all iciihout exceptmi completed the 

 change and became Airiblystomas. Only one of them, No. I., showed by con- 

 stant swimming on the surface, which was noticed at the end of the sixth 

 month, a distinct inclination to the change, a preference for breathing 

 with the lungs. Of this individual, therefore, it may well be assumed, 

 that also without artificial aid it would have come to the land and have 

 undergone the transformation, just as was the case in some thirty spec- 

 imens which Dumeril observed. 



