THE RECAPITULATION THEORY 339 



whoever his ancestors may have been, in regard to 

 his ear muscles ; for he possesses these in a rudi- 

 menTarjTand functionless condition, which can only 

 be e'xpfeified by descent from some better equipped 

 progenitor. 



Closely connected with the question of degenera- 

 tion is that of the size of animals, and its bearing 

 on their structure and development a problem 

 noticed by many writers, but which has perhaps 

 not yet received the attention it merits. 



If we are right in interpreting the eggs of 

 Metazoa as representing the unicellular or protozoon 

 stage in their ancestry, then the small size of the 

 egg may be viewed as recapitulatory. But the 

 gradual increase in size of the embryo, and its 

 growth up to the adult condition, can only be 

 regarded as representing in a most general way, if 

 at all, the actual or even the relative sizes of the 

 intermediate ancestral stages of the pedigree. 



It is quite true that animals belonging to the 

 lower groups are, as a general rule, of smaller size 

 than those of higher grade ; and also that the giants 

 are met with among the highest members of each 

 division. Cephalopoda are the highest molluscs, 

 and the largest cephalopods greatly exceed in size 

 any other members of the group ; decapods are at 

 once the highest and the largest crustaceans ; and 

 whales, the hugest animals that exist, or so far 

 as we know, that ever have existed, belong to the 

 highest group of all, the mammalia. It would be 

 easy to quote exceptions, but the general rule 

 obtains admittedly. However, although there may 



