488 



IMMATURE. 



INDEX. 



JACQUINOT. 



i. 44 ; tendency to, in monkeys, 



microcephalous idiots and savages, 



i. 56 ; influence of, i, 161. 

 Immature plumage of birds, ii. 183, 



187. 

 Implacentata, i. 202. 

 Implements, employed by monkeys, 



i. 51 ; fashioning of, peculiar to 



man, i. 52. 

 Impregnation, period of, influence of, 



upon sex, i. 303. 

 Improvement, progressive, man alone 



supposed to be capable of i. 49. 

 Incisor teeth, knocked out or filed 



by some savages, ii. 340. 

 Increase, rate of, i. 131 ; necessity of 



checks in, i. 135. 

 Indecency, hatred of, a modern 



virtue, i. 



96. 



India, difficulty of distinguishing the 



native races of, i. 215 ; Cyprinidse 



of, ii. 17 ; colour of the beard in 



races of men of, ii. 319. 

 Indian, North American, honoured 



for scalping a man of another tribe, 



i. 93. 

 Individuality, i. 62. 

 Individuation, i. 318. 

 Indopicus carlotta, colours of the sexes 



of, ii. 175. 

 Infanticide, prevalence of, i. 94, 



134 ; supposed cause of, ii. 344 ; 



prevalence and causes of, ii. 363 



et seq. 

 Inferiority, supposed physical, of 



man, i. 156. 

 Inflammation of the bowels, occur- 

 rence of, in Cebtis Azarse, i. 12. 

 Inheritance, i. 110; of effects of use 



of vocal and mental organs, i. 58 ; 



of moral tendencies, i. 102, 104 ; of 



long and short sight, i. 118 ; laws 



of, i. 279; sexual, i. 285; sexually 



limited, ii. 154. 

 Inquisition, influence of the, i. 179. 

 Insanity, hereditary, i. 111. 

 Insect, fossil, from the Devonian, i. 



360. 

 Insectivora, ii. 286 ; absence of 



secondary sexual characters in, i. 



268. 

 Insects, relative size of the cerebral 



ganglia in, i. 145 ; male, appearance 

 of, before the females, i. 260 ; pur- 



suit of female, by the males, i. 

 272 ; period of development of 

 sexual characters in, i. 291 ; secon- 

 dary sexual characters of, i. 341 ; 

 stridulation of ii. 331. 

 Insessorks, vocal organs of, ii. 55. 

 Instep, depth of, in soldiers and 



sailors, i. 117. 

 Instinct and intelligence, i. 37. 

 Instinct, migratory, vanquishing the 

 maternal, i. 83, 90. 



Instinctive actions, the result of in- 

 heritance, i. 80. 



Instinctive imp^^lses, difference of 

 the force of, i. 87, 89 ; and moral 

 impulses, alliance of, i. 88. 



Instincts, i. 36 ; complex origin of, 

 through natural selection, i. 38 ; 

 possible origin of some, i. 38 ; ac- 

 quired, of domestic animals, i. 79 ; 

 variability of the force of, i. 83 ; 

 difference of force between the 

 social and other, i. 89, 104 ; utilised 

 for new purposes, ii. 335. 



Instrumental music of birds, ii. 61, 

 66. 



Intellect, influence of, in natural 

 selection in civilised society, i. 171. 



Intellectual faculties, their influ- 

 ence on natural selection in man, i. 

 158; probably perfected through 

 natui'al selection, i. 160. 



Intelligence, Mr. H. Spencer on the 

 dawn of, i. 37. 



Intemperance, no reproach among 

 savages, i. 96 ; its destructiveness, 

 i. 172. 



Intoxication in monkeys, i. 12. 



Iphias glaucippe, i. 394. 



Iris, sexual difference in the colour of 

 the, in birds, ii. 72, 128. 



Iscnio-PUBic muscle, i. 127. 



Ithaginis cruenttis, number of spurs 

 in, ii. 46. 



lulus, tarsal suckers of the males of, 

 i. 340. 



J. 



Jackals learning to bark from dogs, 



i. 44. 

 Jack-snipe, coloration of the, ii. 226. 

 Jacquinot, on the number of species 



of man, i. 226. 



