/- 



NOTES. 



regularly on its course of development from the egg, 

 but instead of passing from the aquatic gilled con- 

 dition to the terrestrial gill-less adult form of the Sala- 

 mander, 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 loco- 

 motive organ, a highly-developed eye, a relatively 

 large nervous system. The former may be compared 

 to a permanent childishness, the latter to the second 

 childhood, which is really atrophy and decay. It is 

 highly probable that super-larvation has taken place 

 at various epochs and in various groups of the 

 animal kingdom, just as it does in axolotl, and yet 

 we cannot hope for evidence fitted to establish its 

 occurrence in any one case, where it is no longer 

 possible by exceptional conditions to recover (as in 

 the case of axolotl, which can experimentally be 

 made to advance to the Salamander phase by 

 proper treatment), the discarded, more developed 

 adult form. By super-larvation it would be possible 

 for an embryonic form developed in relation to 

 special embryonic conditions and not recapitulative 

 of an ancestry, to become the adult form of the 

 race, and thus to give to the subsequent evolution 

 of that race a totally and otherwise improbable 

 direction. 



