INDEX. 5i$ 



Marriage, after the age of puberty, is the natural ftate of 

 man, 271. Difadvantages of too eariy marriages, til 5, 

 Bad efFedts of interefted and imprudent ones, 275. Argu- 

 ments in favour of monogamy, 282, 283. 



Martin. Mr. Hunter's account of the free-martin, 218, 2-19. 



Martins are birds of paflage, 481, 



Mafon-bee. See bee. 



Matter. Its vis inertiae, 140. 



Mechanifm inadequate to account for animal a^Ttion, S39. 



Medufa defcribed, 110. Its motions, 150. ' 



Memory of children is weak, and why, 209. 



Metamorphofes. See transformations. 



Migration of animals, 476. Lifts of birds of pafTage, with 

 the times of their arrival and departure, 487, &c. Partial 

 migrations, 494. Principal obje61s of migration, 495, 505. 

 Men have a principle of migration, 496. Quadrupeds like- 

 wife perform partial migrations, 497. Migration of rats, 

 ibid. ; of frogs, 497 *, of fiihes, ibid. ; of land-crabs, 502. 

 of infeas, 504. 



Millipes multipUes by fpontaneous feparation, 41. 



Mind. Its faculties the chief fource of animal power. Hi. 

 Minds of brutes poflefled of original qualities, 163. The 

 loweft fpecies of animals are endowed with minds, 164. 

 The mind of man undergoes changes, 292. 



Minerals, no analogy between them and vegetables, 24. 



Modefty. The great defence and ornament of women, 243 

 244. Is not confined to the human fpecies, 244. 



Moles. Defcription of their manners and operations, 323. 



Monkeys. When fleeping, one acls as a centinel, 404. 



Motacilla. See titmoufe. 



Moths. An account of them, 102. Divided into two kinds, 

 the fphinx and phalaena, ibid. All of them, when about 

 to transform, fpin cods or clues of lilk, 303. 

 Motion. Spontaneous motion, 140. By what inftrument it 

 is performed, 141. Vital and involuntary motions, 142. 

 Motions of animals proportioned to their weight and ftruc- 

 ture, 143. Motion gives animation and vivacity to the 

 whole fcene of Nature, 144. Deftruftive animals flower 

 in their motions than the weaker kinds, 145. Progreflive 

 motion of the mufcle, ibid. Motions of the razor or fpout- 

 fifh, 147 ; of the fcallop, 148 •, of the oyftcr, 148; of the 

 fea-urchin, 149 j of the medufa, or fca-ncttlc, 150. Mo- 



