S4.f INDEX. 



2.39; but, among infefts, the difference often great, ibid. 240, 241. Of the fu.ppo- 

 fed lex'?s of plants, 245. The arguments employed to fupport the fexes of plants 

 are entirely analogical, 246. Thefe analogies fliown to be without foundation, ibjd. 

 247. Some of them ridiculous^-248. The moft plaufible argument in fupport of 

 vegetable fexes derived foom the culture of the date-bearing palm, ibid. This csr- 

 cumftance brings no aid to the fcxualift, 249. Mylius's experiment on the Berlin 

 palm imperfect and inconclufive, 249, 250. Sexualifts have recourfe to the winds 

 and to infefts for the impregnation of certain plants, 250. This notion refuted, 2?i, 

 252. ArRument from new varieties examined, 253. Dr Hope's experiments on the 

 Jychnis dioica examined, 254. Spalanzani's experiments on the fexes of plants, 259, 

 — 262. Changes produced in animals by puberty, 264. The male bees impregnate 

 the eggs after they are depofited in the cells, 344. 

 Sheep alTociate, and defend each other, 433. Their origin, 460. 

 Showers of blood accounted for, 302. 

 Silk-worms. See worms and caterpillars. 

 Skeletons, of all quadrupeds, when raifed on their hind-legs, have a great refemblance 



to thofe of man, 54. 

 Sleep, of plants, 6. 



Smeathman. His account of the termites or wood-ants, 359. 

 Smelling. See fenfes. 

 Snails. Their mode of refpiring, 124, 125. 



Society. Not confined to the human fpedes, 414. Its origin, ibid. The affociating 

 principle is inftinftive, 416. Its advantages, ibid. Gives rife to many virtues and 

 iources of happinefs, 41 7. Its difadvantages, 418. Without aflbciation, men could 

 perform no extenilve operations, ibid. Society of the beavers, 419; of pairing 

 birds, 420 ; of the honey-bees, 421 ; of the common caterpillars, 425; of the pro- 

 ceflionary caterpillars, 427. Some caterpillars are republicans, 429. Society of ants, 

 430; of gregjrious animals who carry on no common operations, 432. 

 Sound. Its medium and caufes, 168. The celerity of its motion, 169. Augmented 



by refleftion, 170. Its modifications, ibid. 

 Spalanzani. Account of his experiments upon digeftion, 225. His experiments on 



the fexes of plants, 259. 

 Sparrows of great ufe by devouring nunibers of caterpillars, 395. 

 Speech. See language. 

 .Sphinx. See moth. 



Spiders. Their ftrufture and manners, 98. When terrified fimulate death, 149. 

 Their attachment to their young, 274. Moft vor.icious animals, 383. Some furvive 



.the winter, 411. 



Spider- 



