34 8 ANIMAL DEVELOPMENT 



superficially unlike their parents. But this is largely due to their 

 featherless condition, and they are obviously of bird nature, so 

 not entitled to be called larvae. 



In applying the law of recapitulation to animals possessing a 

 larval stage in their life-history, there is special need to exert care 

 in making deductions as to the characters possessed by ancestral 

 forms. There is great likelihood of organs developing out of their 

 proper order, for those which are absolutely necessary to the life 

 of the larva when it begins an independent existence take pre- 

 cedence of others which are not of such vital importance in the 

 struggle for existence. This is particularly true for organs of 

 locomotion and digestion, while few larvae would survive if the 

 nervous system and sense organs were not in an efficient state. 

 Such parts of the body have to hurry up, as it were, or in other 

 words there is a "hastening of events ". Larvae are also very apt 

 to possess secondary characters, i.e. features specially related to the 

 exigencies of larval life, which frequently differs in a marked way 

 from adult existence. And it is obvious that such characters often 

 afford no clue to the nature of ancestral forms. 



