510 LAWS OF MULTIPLICATION. 



To every reader there will probably occur the seemingly- 

 adverse evidence furnished by the Irish; who, though not 

 well fed, multiply fast. Part of this more rapid increase is 

 due to the earlier marriages common among them, and con- 

 sequent quicker succession of generations — a factor which, 

 as we have seen, has a larger effect than any other on the 

 rate of multiplication. Part of it is due to the greater 

 generality of marriage — to the comparative smallness of the 

 number who die without having had the opportunity of pro- 

 ducing offspring. The effects of these causes having been 

 deducted, we may doubt whether the Irish, individually con- 

 sidered, would be found more prolific than the English. 

 Perhaps, however, it will be said that, considering their diet, 

 they ought to be less prolific. This is by no means obvious. 

 It is not simply a question of nutriment absorbed. It is a 

 question of how much remains after the expenditure in self- 

 maintenance. Now a notorious peculiarity in the life of the 

 Irish peasant is, that he obtains a return of food which is 

 large in proportion to his outlay in labour. The cultivation 

 of his potatoe-ground occupies each cottager but a small part 

 of the year ; and the domestic economy of his wife is not of a 

 kind to entail on her much daily exertion. Consequently the 

 crop, tolerably abundant in quantity though innutritive in 

 quality, possibly suffices to meet the comparatively-low ex- 

 penditure, and to leave a good surplus for genesis — perhaps 

 a greater surplus than remains to the males and females of 

 the English peasantry, who, though fed on better food, are 

 harder worked. 



We conclude, then, that in the human race, as in all other 

 races, such absolute or relative abundance of nutriment as 

 leaves a large excess after defraying the cost of carrying on 

 parental life, is accompanied by a high rate of genesis.* 



§ 367. Evidence of the converse truth, that relative in- 



* This is exactly the reverse of Mr. Doubleday's doctrine ; which is that 

 throughout both the animal and vegetable kingdoms, "over-feeding checks 

 increase ; whilst, on the other hand, a limited or deficient nutriment stimu- 



