/ 



l66 Darwin and Romanes dealt witli. 



in his admirable and able book on Lonf^evity. He 

 points out that a very large number of organisms die 

 at once on reproduction, " by the rapid abstraction 

 of the matter of life contained in the eggs and sperm 

 — Protozoa, insects and annual plants." Traces of 

 the same law are to be found in much higher ranks 

 of existence, and among highly differentiated creatures 

 — in fact, the higher you go in this, the more illustra- 

 tions you find. For example, as Dr. Lankester puts 

 it, " Among birds, smaller broods go with a greater 

 longevity." He finds the same thing, to a certain 

 extent among fishes ; writing : 



" In fishes, which give personal attention to young, 

 the bulk and number of young are immensely reduced. 

 The pipe-fish (which carries its young in a pouch, and 

 the tube-mouth, which does the same — only the 

 father in the one case, and the mother in the other) — 

 the Hippocampus and Arius of the Amazons. He 

 also finds corroboration of the principle in mules and 



I ^ cut animals, which confirm the hypothesis that 



I I generative expenditure antagonises longevity." '•' 



It is the same among certain of the parasitic 

 worms. Van Beneden says, in addition to what we 

 have already noted : 



" Between the true hermaphrodites and the true 

 diaecious worms are found species in which the males 

 gradually dwindle and become dependent on the 

 female ; this is to be seen in the Sphenilaricc, among 

 which the male is only an appendage to the female 

 sex. We find here full evidence of the fact that the 

 female is inore important than the male ivith regard to 

 the preservation of the species. In some species the 



* Longevity, p. 76. 



