NECESSARY TRUTHS— EFFECTS OF EXPERIENCE. 683 



The udders and permanent milk of the domestic breeds 

 of cow. 



The ' fancy ' rabbit's ears, drooping through lack of 

 need to erect them. Dog's, ass's, etc., in some breeds 

 ditto. 



The obsolete eyes of mole and various cave-dwelling 

 animals. 



The diminished size of the wing-bones of domesticated 

 ducks, due to ancestral disuse of flight.* 



These are about all the facts which, by one author or 

 another, have been invoked as evidence in favor of the 

 ' lapsed intelligence ' theory of the origin of instincts. 



Mr. Darwin's theory is that of the natural selection of 

 accidentally produced tendencies to action. 



" It would," says he, " be the most serious error to suppose that the 

 greater number of instincts have been acquired by habit in one genera- 

 tion, and then transmitted by inheritance in succeeding generations. 

 It can clearly be shown that the most wonderful instincts with which 

 we are acquainted, namely, those of the hive-bee and of many ants, 

 could not possibly have been thus acquired. f It will be universally ad- 

 mitted that instincts are as important as corporeal structure for the wel- 

 fare of each species, under its present conditions of life. Under changed 

 conditions of life, it is at least possible that slight modifications of in- 

 stinct might be profitable to a species ; and if it can be shown that in- 

 stincts do vary ever so little, then I can see no difficulty in natural 

 selection preserving and continually accumulating variations of instinct 

 to any extent that may be profitable. It is thus, as I believe, that all 

 the most complex and wonderful instincts have arisen. ... I believe 

 that the effects of habit are of quite subordinate importance to the effects 

 of the natui-al selection of what may be called accidental variations of 

 instincts ; — that is, of variations produced by the same unknown causes 

 which produce slight deviations of bodily structure." % 



* For these and other facts cf . Th. Ribot : De l'Heredit6 ; W. B. Car- 

 penter : Coutemporary Review, vol. 21, p. 295, 779, 867; H. Spencer: 

 Princ. of Biol. pt. ii. cb. v, viii, ix, x; pt. in. ch. xi, xil ; C. Darwin: 

 Animals and Plants uuder Domestication, ch. xii, xiir, xrv ; Sam'l But- 

 ler : Life and Habit ; T. A. Knight : Philos. Trans. 1837 ; E. Dupuy : 

 Popular Science Monthly, vol. xi. p. 332 ; F. Papil'lou : Nature and Life, 

 p. 330; Crothers, in Pop. Sci. M., Jan. (or Feb.) 1889. 



f [Because, being exhibited by neuter insects, the effects of mere prac« 

 tice cannot accumulate from one generation to another. — W. J.] 



:|: Origin of Species, chap. vii. 



