114 METAMOKPHOSES OF MAN 



tions to the general rule. Animals which undergo meta- 

 morphoses^ almost always grow after birth, just as in 

 the case of man. Many of them are like certain ovi- 

 para, and grow during the whole of their lives. Hence 

 it is not surprising that the differences of weight and 

 volume between young and old individuals should be 

 greater than it is among vivipara. At the age of 

 twenty, man is rarely four times as long as the new- 

 born infant ; and his average weight is hardly thirty 

 times greater. The Teredo larva, which is about to 

 undergo a change of form, is four thousand times 

 larger than when it sprung from the egg, and is still 

 many million times smaller than its mother.* 



There is another fact of a more decisive nature 

 which shows the embryonic character of the larva. 

 We saw in an earlier chapter that every monstrosity 

 is congenital, and is referable to a period when the 

 embryonic development is going on. We have fre- 

 quently seen monster insects. Instances of herma- 

 phrodite insects are common enough in entomological 

 collections, for amateurs carefully preserve these in- 

 teresting specimens instead of delivering them to the 

 anatomist's scalpel. Sometimes, however, we meet 

 with persons actuated by a more truly scientific spirit : 

 it was in this way that Eudolphi was enabled to dis- 



* Indefinite growth during the entire life of the individual is 

 met with only among the lower species of the superior animals. 

 Thus, among vertebrates this peculiarity is presented only by cer- 

 tain fishes and reptiles. In these even, the growth slackens con- 

 siderably as life is prolonged : we may observe this occasionally 

 in the carp. I once saw one of these fish which was said to have 

 been transmitted in a fisherman's family, from father to son, for 

 more than a hundred years. It was hardly longer than an ordinary 

 carp, but was much thicker. 



