OF NATURAL HISTORY. 245 



mals, both fexes are combined In each individual. The earth- 

 worm, fnails, and feveral fliell-fifhes, are hermaphrodites ; 

 and vet the conjundllon of two is neceflary for their multi- 

 plication. Mr. Adanfon, in his account of Senegal, men- 

 tions fome fliell-anlnials which, in order to produce, require 

 the union of three individuals. In the polypus, no appear- 

 ance of fcxual diftlnc^Ion has hitherto been difcovered. 

 Nature, however, has not denied them the power of multi- 

 plication, which is efFedled in a very fingular manner*. Cater- 

 pillars of every denomination are totally deftitute of fexes, 

 and are incapable, while they remain in that ftate, of mul- 

 tiplying their fpecies. But, after their transformation into 

 Hies, the diftindlion of fexes is apparent, and their fertility 

 is exceedingly great* 



Among the larger animals, the difference of fize and 

 figure between males and females is not remarkable. The 

 moft ftriking difi:in(Stions arife from the horns, the tufks, the 

 creft, Sec. which adorn the head of the male, and are often 

 wanting in the female. « But, among the infecSt tribes, fome 

 males differ fo greatly from the females, that they have the 

 appearance of belonging to a feparate genus. In fome but- 

 terflies, for example, the female is deftitute of wings, while 

 thofe of the male are very large. The male and female of 

 thofe animals called gall-infecls bear no proportion to each 

 other, either in fize or in figure. They adhere for feveral 

 months to the flems and branches of plants, fhrubs, and 

 trees, without any apparent movement. They have every 

 appearance of galls, being of a fpherical or oval figure, from 

 which circumftance they have received their denomination, 

 and were long confidered as vegetable fubftances deftitute of 

 every degree of animation. Reaumur, however, by a ftri^l 

 examination of the changes they undergo, and of their in- 

 ternal ftru(Sl:ure, difcovered that they belong to the animal 



* See chap. i. page 30, &c. 

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