56 DEGENERATION : I 



lotl, where the larval form of a Salamander develops 

 generative organs, and is arrested in its further pro- 

 gress to the adult parental form. It is not possible 

 to class this with the other phenomena which I have 

 enumerated as Degeneration, since there is no modi- 

 fication of an adult structure, but simple arrest, and 

 retention of the larval structure in all its completeness. 

 I should call the phenomenon exhibited by the axolotl 

 " arrest " or " super-larvation " rather than degenera- 

 tion. 



The result of super-larvation is in so far similar to 

 that of those changes to which it is desirable to 

 restrict the term " degeneration," that it may be 

 classed under " simplificative evolution " as opposed 

 to " elaborative evolution/' That there is a very real 

 difference between super-larvation and degeneration 

 may best be seen by taking a case of each process and in- 

 stituting a comparison. The axolotl proceeds regularly 

 on its course of development from the egg, but instead 

 of passing from the aquatic gilled condition to the 

 terrestrial gill-less adult form of the Salamander, it 

 remains arrested in the earlier condition, develops its 

 reproductive organs, and propagates itself. There is 

 no loss or atrophy in this case, but simply a dead stop 

 in a progressive course. On the other hand, as we 

 have seen, the Ascidian loses, by a process of atrophy 

 and destruction, a powerful locomotive organ, a 

 highly -developed eye, a relatively large nervous 

 system. The former may be compared to a perma- 

 nent childishness, the latter to the second childhood, 

 which is really atrophy and decay. It is highly prob- 



