594 Studies in the Theory of Descent. 



of .the Amblystomas bred from Axolotls is at- 

 tributable to " bad nourishment," is obviously of 

 but little avail. How is it that the Axolotls, which 

 are fed in a precisely similar manner, propagate so 

 readily ? Moreover, I am able to expressly assert 

 that my Amblystomas were very well fed. It is 

 true that they have as yet scarcely reached the 

 age of two years, but the Axolotl propagates 

 freely in the second year, and some of Dume"rirs 

 Amblystomas were five years old in 1870. 



This fact of the sterility is strongly opposed to 

 the idea that these Amblystomas are the regular 

 precursors of the phyletically advancing genus 

 Siredon* 1 I will by no means assert that my 



M [Eng. ed. It was mentioned in the German edition of 

 this work that in the spring of 1876 a female Amblystoma of 

 the Jardin des Plantes in Paris had laid eggs (see Blanchard in 

 the Compt. Rend. 1876, No. 13, p. 716). Whether these eggs 

 were fertile, or whether they developed was not then made known. 

 Thus much was however at the time clear, that even if this 

 had been the case, the reproduction of this Amblystoma would 

 have been only an exceptional occurrence. At that time there 

 were in the Jardin des Plantes Amblystomas which had been 

 kept for more than ten years, and only on one occasion was 

 there a deposition of eggs, and this by only one specimen. 

 That I was correct in speaking of the " sterility " of these 

 Amblystomas in spite of this one exception, is proved by the 

 latest communication from the Jardin des Plantes. We learn 

 from this (Compt. Rend. No. 14, July, 1879, p. 108) that in 

 the years 1877 and 1878 none of the Amblystomas laid any 

 more eggs, although all means were exerted to brjng about 

 propagation. In April, 1879, eggs were again laid by one 

 female, and by a second in May. These eggs certainly de- 

 veloped, as did those of 1876, and produced tadpoles. These 



