Miscellaneous. 447 



a peculiar interest inasmuch as it confirms the justice of Cuvier's 

 supposition when he said, without having been able to obtain any 

 direct proof of it, that the axolotl, although regarded as a Perenni- 

 branchiate Batrachian, would prove to be a larva. 



I have not time to enter upon an examination of the different 

 questions which arise from these unexpected observations, which 

 have been made for nearly two years at the menagerie, the most 

 important of which, in a physiological ])oint of view, is, undoubtedly, 

 that which demonstrates the development of the generative power in 

 animals which have not yet arrived at their definitive form. These 

 observations have been published in the ' Nouvelles Archives du 

 Mnse'um' (tome ii. pp. 26.5-292, pi. 10). 



I now take the liberty of submitting a summary account of some 

 experiments to which I was led by the study of the facts just 

 indicated. The atrophy of the branchial tufts and their gradual dis- 

 appearance being the first signs of the metamorphosis which is going 

 to take place, I have endeavoured to provoke a change in the mode 

 of respiration by obliging the animals to make use of their pulmonary 

 organs. I made at first some fruitless experiments, consisting partly 

 in gradually diminishing the quantity of water in which the axolotls 

 were kept, so as to leave them, after a certain time, nothing but a 

 layer of damp sand, and partly in arranging in their aquarium a 

 broad shelter, which enabled them to live alternately immersed and 

 out of the liquid. 



To obtain &ny result there was another experiment to be made. 

 It was necessary to destroy the branchiae, in order to ascertain 

 whether, when rendered compulsorily animals with a pulmonary 

 respiration, the axolotls would undergo the modifications which I 

 have enumerated. 



Accordingly, on the 4th of July 1866, I completely removed the 

 three branchial stalks on the left side in two axolotls, and those of 

 the right side in a third; then, from the i4th to the 28th, I cut 

 off every week one of the branchial stalks of the opposite side. 

 At this last date the axolotls would have been entirely deprived of 

 the branchiae if, during the twenty-four days which had elapsed 

 since the first operation, the astonishing power of regeneration with 

 which the Urodelous Batrachia are endowed had not caused the 

 commencement of a reproduction of the organs which had been re- 

 moved. Therefore, in order to keep the axolotls in the state in 

 which I wished to place them, so that I might appreciate the results 

 of the experiment, I cut away successively, on either side, the new 

 branchial stalks as soon as they began to project suflficiently to be re- 

 moved by the scissors. From the 28th of July 1866 to the 24th of 

 May 1867 (that is to say, a period of ten months), I was obliged 

 to operate, either on the right or left side, three, four, or even five 

 times. During the winter the reproduction was much slower. 



On the 10th of August 1866, I cut off the three branchial stalks 

 of the right side of six axolotls, and, wishing to exert a more general 

 and rapid action, on the 1 7th also the three branchiae of the left 

 side. As in the other casts, there was scarcely any haemorrhage. 



