PEOPLING OF LAND AND SEA 161 



are entirely incapable of nourishing themselves. 1 Among the 

 marine Worms, such as Bonellia, the female is as large as a 

 nut, while the males are so small that they were once taken 

 for Infusorians living as parasites on the female organ, where 

 they are found to the number of seven or eight. 



At first sight there seems to be a contrast between this 

 diminution in size and the splendour which the males attain in 

 other cases, and also a contradiction between this diminution 

 in size and the abortive forms so noticeable among certain 

 females. In the Glow-worm, 2 many night-flying Lepi- 

 doptera, 3 and Stylops, the females are without wings. In 

 the last case they are reduced to egg-sacs, and only 

 their almost formless heads protrude outside the body of 

 the wasp, in which they live as parasites. But all these 

 apparently paradoxical facts range themselves under one and 

 the same principle. It is the development and the nutrition 

 of the eggs, that is to say the accumulation of reserve sub- 

 stances in the cells still belonging to the mother, and perhaps 

 also the organism's disuse of its wings when it has become too 

 heavy for them, that has brought about the reduction and 

 disappearance of these organs in the Glow-worm and various 

 female Lepidoptera. The same causes have determined the 

 parasitism of the females of Stylops, a parasitism that has 

 brought with it, as usual, the complete decay of the locomotor 

 apparatus. Here we have a phenomenon analogous to that 

 which has been observed in the Chondracanthidae, which 

 are Copepod Crustaceans, and Bopyridae, which are Isopods. 

 The males, a hundred times smaller than the females, 

 which are almost formless and parasitic, remain attached like 

 minute lice to the abdomen of the latter. These female 

 Bopyridae are frequently found under the carapace of Shrimps, 

 which they raise into an irregular swelling on one side. In 

 another family of Copepods, the Lernaeidae, the males and 

 females, at first small and almost alike, are coupled together ; 

 the males then disappear and the females parasitically attach 

 themselves to the gills or other organs of some Fish, where they 

 become enormous, almost limbless, and so unrecognizable 

 that Cuvier classed them among the Worms. 



From all this it follows that individuals of the male sex are 



1 Mosquitoes. 



2 Lampyris noctilnca. 



3 Orgyia antiqua, Psyche helix, Cheimatobia brumata, etc. 



M 



