264 THE PRINCIPLES OF Part II. 



inequality is greater than with any other animal, for 

 during twelve years, out of 6878 births, the male births 

 have been as HO'l to 100 female births. It is, however, 

 in some degree doubtful whether it is safe to infer that 

 the same proportional numbers would hold good under 

 natural conditions as under domestication ; for slight 

 and unknown differences in the conditions affect to a 

 certain extent the proportion of the sexes. Thus with 

 mankind, the male births in England are as 104*5, 

 in Kussia as 108'9, and with the Jews of Livonia as 

 120 to 100 females. The proportion is also mysteriously 

 affected by the circumstance of the births being legiti- 

 mate or illegitimate. 



For our present purpose we are concerned with the 

 proportion of the sexes, not at birth, but at maturity, 

 and this adds another element of doubt ; for it is a well 

 ascertained fact that with man a considerably larger 

 proportion of males than of females die before or during 

 birth, and during the first few years of infancy. So it 

 almost certainly is with male lambs, and so it may be 

 with the males of other animals. The males of some 

 animals kill each other by fighting ; or they drive 

 each other about until they become greatly emaciated. 

 They must, also, whilst wandering about in eager search 

 for the females, be often exposed to various dangers. 

 With many kinds of fish the males are much smaller 

 than the females, and they are believed often to be 

 devoured by the latter or by other fishes. With some 

 birds the females appear to die in larger proportion 

 than the males : they are also liable to be destroyed on 

 their nests, or whilst in charge of their young. With 

 insects the female larvae are often larger than those of 

 the males, and would consequently be more likely to be 

 devoured : in some cases the mature females are less 

 active and less rapid in their movements than the males, 



