236 ANIMAL PAEASITES AND MESSMATES. 



question by their persevering researches, and Mons. 

 Claparede expected to invalidate the results obtained by 

 them by establishing himself at Naples, in order to 

 devote himself to a new series of investigations. Contrary 

 to his expectations, he arrived at the same conclusions, 

 and announced that a nereid possesses, in one and the 

 same species, two kinds of males and two sorts of 

 females, and that these males differ from each other, 

 not only in their manner of life but in their age, in the 

 mode of formation of the spermatozoids as well as in 

 the form ; that the females differ no less from each 

 other than the males, and that each form is intended to 

 provide, in its own manner, for the dissemination of the 

 eggs. 



We see this realized in annelid worms known by the 

 name of Heteronereidse. Certain individuals of small 

 size live on the surface of the water ; others, evidently 

 much larger, live at the bottom of the sea and behave 

 quite differently. The eggs and the spermatozoids pro- 

 ceeding from these two forms differ sensibly from one 

 another, and the difference of form corresponds with 

 that of origin. 



We see thus among some of them different males; 

 among others different females : then eggs and sperma- 

 tozoids equally different in one and the same animal 

 species. 



A curious insect, the Termes lucifuga, appears also to 

 distinguish itself by two sorts of males and females, 

 which even take to flight at different periods. Great 

 sagacity was required to reveal these strange facts. 

 Mons. Lespes has had the courage to devote himself 

 to these observations. 



