200 PROCEEDINGS OF THE ACADEMY OF [April, 



more or less with each successive period of reproduction (as the 

 male deer which multiply the number of prongs upon their antlers), 

 it would be the last period of reproduction at which the individual 

 should be classified. In a case of excessive parasitism, many organs 

 (»f the body may have been in degeneration before the time of 

 reproductive activity, yet the organism should not be classified before 

 it is functionally reproductive. And it is correct to consider the 

 organization as a whole as non-senile up to the time of the repro- 

 tluctive activity, since non-senile powers of growth are transmitted 

 to its ova. In cases of complete successive hermaphroditism, where 

 the individual is first functionally male, then hermaphrodite, then 

 female (protandry), or where the succession is the reverse (pro- 

 terogyny), the terminal stage also would be the one at which the 

 individual should be classified, even though, as in many pulmonate 

 Gasteropods, certain organs have during the reproductive period 

 become degenerate (as the genital organs characteristic of the first 

 functional stage). 



Accordingly, in cases where alternation of generations does not 

 occur, the mature or perfected stage from the phyletic standpoint 

 would be found not before the last reproductive period. Generally 

 it would be at that last period, if not always. For even in the 

 case of neotenia, where the reproductive cells are mature before the 

 somatic structure is fully differentiated, such procreative precocity in 

 parasites is evidently only an adaptation to accidents inducing a pre- 

 cocious departure from the body of the last host (as in Gordius), and 

 as a rule the soma has time to differentiate fully before the reproduc- 

 tive elements are deposited. In mammals, neotenia may be said 

 to occur, since considerable somatic differentiation takes place after 

 the first period of reproduction ; but in mammals the case of neo- 

 tenia need not perplex us, since, as has been shown, a mammal is 

 to be classified at the time of its last reproductive period. The 

 organization as a whole is then non-senile until after the last repro- 

 ductive period ; the individual is to be classified at that period, and 

 not before, for classification at a preceding state would not show 

 the full extent of its development. Classification after that stage 

 is not permissible, unless for some cases of neotenia, since cessation 

 of reproductive activity denotes the beginning of senility (catalysis 

 of the organization as a whole), and since after such cessation 

 further changes of the organism could not be transmitted to the 

 offspring. 



