ENVIRONMENT AND FERTILITY 213 



dity of the very poor, even in countries where the 

 general birth-rate is declining, may be connected 

 with a sparseness, or irregularity, of diet which 

 brings into their life something of the conditions 

 of man's natural, or savage, state. The English 

 peerage may fairly be taken to represent condi- 

 tions of ease and luxury : few patents of nobility 

 outlast the course of three centuries. 



It also seems to be true that idleness is prejudi- 

 cial to fecundity. Breeders are well aware of the 

 importance of keeping their stock well exercised. 

 But, in the case of women, labour must not be 

 too fatiguing : their employment in factories 

 appears to lessen their capacity for child-bearing. 

 And disease may, of course, severely check the 

 increase of a population : repeated attacks of 

 fever cause an enfeeblement of virility which 

 may end in impotence. For the rest, the causes 

 which at the present day are lowering the average 

 size of families appear to have more connection 

 with the culture than with the environment of 

 society. 



Environment and the race 



Scientific opinion is sharply divided as to the in- 

 heritance of acquired peculiarities. One school of 

 thought not only insists that peculiarities acquired 

 by the individual may become innate in the race, 

 but regards the acquirement of peculiarities as the 

 principal means by which plants and animals have 

 developed their multiform species. Another school 

 denies that acquired characters are heritable, 

 and is persuaded that the differences which 

 divide one species from another have their origin 

 in spontaneous mutations or variations. It 

 fortifies its conclusion by maintaining that the 

 reproductive tissue or germ-plasm is entirely 

 distinct from the sentient and active body, and 



