PARTHENOGENESIS AND ITS SEQUEL 307 



inability to restore vigour by the more normal method 

 bi reproduction by sexual congress. 



Among the Rotifers the little Wheel-animalcules 

 exhibit an even greater vitality, for not only can their eggs 

 withstand prolonged desiccation, but in some the body of 

 the animal survives even harsher treatment. If specimens 

 be enclosed within a chamber containing a little sand or 

 moss the contents may be dried over sulphuric acid, or 

 heated up to 200° F., or left to the neglected dust of 

 years, and will yet revive if a little fresh water be added 

 to the sand. Males are rare, and when they do occur 

 are little more than animated receptacles for semen, for 

 they are incapable of feeding, the gullet and digestive 

 tract being reduced to a solid cord. A certain amount 

 of nourishment, however, may be absorbed through the 

 delicate body wall. 



The degeneration of the males in these parthenogenetic 

 species irresistibly reminds one of the smile of the Cheshire 

 cat ; they grow smaller and smaller, and their functions 

 less and less, till finally nothing is left. The " comple- 

 mental males " discovered years ago by Darwin in the 

 Barnacles well illustrate this process. In dissecting adult 

 specimens of the stalked Barnacle (Scalpdlum) he found, 

 just inside the valves, in a pocket of the mantle, a varying 

 number of " complemental males," tiny organisms which 

 Mr. Geoffrey Smith describes as " little more than bags 

 of spermatozoa," and they apparently serve to fertilize 

 the ripe ova of the larger animal — one cannot say of the 

 female, for Scalpellum, like most of the Barnacles, is 

 hermaphrodite. But it is believed that these comple- 

 mental males are really arrested hermaphrodites. At 

 any rate, if it so be noted that with some of the Barnacles, 

 as with some other Crustacea, the larvae are males, but 



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