INDEX. J3.7 



lofplration. See refpiratlon. 



Inftinft. Reafons why it has been fo little underftood, 144. Divifion of inftinSs, 

 145. Of pure inflinfts, ibid. Examples of it in the human fpecies, ibid.; in the 

 brute creation, 146. Of iiiilinfts which can accommodate themfelves to peculiar 

 circuinftances, 150. Of inftin£ts which are improveable by experience and obferva- 

 tion, 152, 154. Superiority of man arifes from his great number of inftindts, 152, 

 Examples of modified, compounded, or extended ipftlnfls, 153. Inftinft defined 

 and explained, 155. Infefts have few inftindls, ibid. Inftinft prefuppofes a degree 

 of intellett, 421. The gradual progrefs of inftindts in children, 435, When they 

 begin to reafon with fome propriety, 436. The education of animals depends great- 

 ly on the principle of imitation, 470. 



Irritability defcribed, 10. Many plants are endowed with this power, 1 1. 



L 



Lady-fly. See libella. 



Language. Moft animals can exprefs their wants and defires, 110,157,172. Artifi- 

 cial a refult of natural language, 172. The origin of the great diverfity of langua- 

 ges, 173. Articulate language peculiar to man, 4 1 7. 



Laplanders- Live chiefly on the rein-deer, 215. Fond of bear's flefli, ibid. 



Laughing defcribed, 109. Not peculiar to man, ibid. 



Leggs. No animal, except the infeiEl: tribes, have more than four, 84, 



Libella. A defcription of it, 93. Its nymph refpires water, 122. A rapacious animal, 



384- 

 Life. Our ignorance of its efl"ential charafteriftics, 9. Its duration longer or fliorter 



according to the fpecies, 41. Life very precarious in infancy, 201. Lives of winged 



infefts confift of three principal periods, 293. Life cannot be fupported without 



the intervention of death, 390. A profufion of animal life feems to be a geneial 



intention of Nature, 392. Of the duration of life in man and other animals, 504, 



S-'c. Its duration a relative idea, 519. 

 Light. Some of its properties, 179. Its refran^ibility, 180. 

 Lobfters caft their (hells annually, 290. 

 Longevity of animals, 504. Some remarkable inftances of it in the human fpecies, 



506; of fiflies, 509, 513; of quadrupeds, 51 1 ; of a toad, 514 ; of infefts, 5 1 6 ; of 



plants, 5 1 7. 

 Loufe. Its ftruiflure and manners, 97. 

 Love. The fource of many important advantages, 269. Is a great incentive to virtue, 



ibid. 270. Bad effefts of too early marriages, 270; and of imprudent ones, 271. 



Love of offspring a fource of great pleafures, 272; remarkable inftances of its 

 .j. 3 Y ftrengtli. 



