FERTILITY 591 



times Buff on, 1 among others, remarked on the fact that domestic 

 animals breed oftener and produce larger litters of young than 

 wild animals belonging to the same species ; and Darwin, who 

 made the same observation, attributed the increased fertility 

 of the former to a long habituation to a regular and copious 

 food supply without the labour of seeking for it. " It is notorious 

 how frequently cats and dogs breed, and how many young they 

 produce at birth. The wild rabbit is said to breed four times 

 yearly, and to produce each time at most six young ; the tame 

 rabbit breeds six or seven times yearly, producing each time 

 from four to eleven young. . . . The ferret, though so closely 

 confined, is more prolific than its supposed wild prototype [the 

 polecat]. The wild sow is remarkably prolific ; she often breeds 

 twice in the year, and bears from four to eight, and sometimes 

 even twelve, young ; but the domestic sow regularly breeds 

 twice a year, and would breed oftener if permitted ; and a sow 

 that produces less than eight at birth ' is worth little, and the 

 sooner she is fattened for the butcher the better/ The amount 

 of food affects the fertility of the same individual ; thus sheep 

 which on mountains never produce more than one lamb at birth, 

 when brought down to lowland pastures frequently bear twins. 

 The difference apparently is not due to the cold of the higher 

 land, for sheep and other domestic animals are said to be 

 extremely prolific in Lapland." 2 



Darwin remarks that birds afford still better evidence of 

 increased fertility resulting from domestication. Thus, in its 

 natural state the female of Gallus bankiva, the wild representative 

 of the common fowl, lays only from six to ten eggs ; the wild 

 duck lays from five to ten eggs, as compared with eighty or a 

 hundred produced by the domestic duck in the course of the 

 year. Similarly, the turkey, the goose, and the pigeon are more 

 fertile in the domestic state, though this is not the case with 

 the pea-fowl. Among plants also there are countless instances 

 of increased fertility as a consequence of cultivation. 3 



1 Buffon, Histoire Naturelle, Paris, 1802. 



2 Darwin, The Variation of Animals and Plants under Domestication, 

 Popular Edition, vol. ii., London, 1905. 



3 Cf. also Spencer (he. cit.), who discusses this question at some length 

 in connection with his generalisation that Individuation and Genesis vary 

 inversely. See above, p. 587. 



