I N I) E X. 5ifi 



lmperfe£l and inconclufive, 255y 256, Sexualifts have rcy 

 courfe to the winds and to infe^ls for the impregnation of 

 certain plants, ^56. This notion refuted, 257, 258. Ar- 

 gument from new varieties examined, 258. Dr. Hope's 

 experiments on the lychnis dioica examined, 260. Spa- 

 lanzani's experiments on the fexes of plants, 264, 265. 

 Changes produced in animals by puberty, 269. The male 

 bees impregnate the eggs after they are depoilted in the 

 cells, 349. 



Sheep alTociate, and defend each other, 436. Their ori- 

 gih, 464. 



Showers of blood accounted for, 306. 



Silk worms. See worms and caterpillars. 



Skeletons, of all quadrupeds, when railed on their hind-legs^ 

 have a great reiemblance to thofe of man;, 63. 



Sleep, of plants, 18. 



Smeathman. His account of tke termites or wood -ants, 364. 



Smelling. See fenfes. 



Snails. Their mode of refpiring, 134, 135. 



Society. Not confined to the human fpecies, 418. Its ori- 

 gin, ibid. The aflbciating principle is inftinftive, 419. Its 

 advantages, ibid. Gives rife to many virtues and fourcej 

 of happinefs, 420. Its difadvantages, 421. Without air 

 fociation, men could perform no extenlive operations, 422. 

 Society of the beavers, 422 ; of pairing birds, 424 ; of 

 the honey-bees, 425 j of the common cTiterpillars, 429 , 

 of the proceflionary caterpillars, 431. Some caterpillars 

 are republicans, 432. Society of ants, 434 5 of gregari- 

 ous animals who carry on no common operations, 436. 



Sound. Its medium and caufes, 176. The celerity of its 

 inotioxi, 177. Augmented by reflexion, 177. Its modi- 

 fications, ibid. 



Spalanzani. Account of his experiments upon digeilxon, 2SC. 

 His experiments on the fexes of plants, 264. 



Sparrows of great ufe by devouring numbers of caterpillar*, 

 S99, 



Speech. See language. 



Sphinx. See moth. 



Spiders. Their ftruclure and manners, 107. When terrili- 

 ed fimulate death, 1 58. Their attachment to their young, 

 278. Moft Yoracious animals, 387. Some furvive th3 

 \vinter, 415. 



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