FECUNDITY. 123 



ply of milk is indicative of, and associated with, en- 

 feebled breeding powers, every care should be taken 

 to obviate this defect." * 



In the human family, as the physical organization, 

 in structure and function, does not essentially differ 

 from that of the lower animals, the same causes of 

 impaired fertility will be operative, if the habits and 

 conditions of life do not present a wide departure 

 from those that prevail in a state of nature. 



With an advance in civilization, however, when 

 the mental faculties attain a high degree of develop- 

 ment, and the physical activity of the system is inten- 

 sified through the action of the nervous system, a new 

 element of variation is introduced, that disturbs the 

 equilibrium of the system and increases the activity 

 of the various causes that interfere with the procrea- 

 tive functions. 



In a work published nearly one hundred years ago, 

 Dr. Black remarked that " high refinement is an ob- 

 stacle to propagation." In a paper read before the 

 Statistical Society, in 1843, Sir John Boileau says: 

 " It is a fact that rich families, taken in general, are 

 those which have the fewest children ; and their ranks 

 would become thinner, generation after generation, if 

 they were not gradually recruited by new families of 

 recently-acquired wealth. 



" The effect which riches have in restraining the 

 fecundity of marriages is nowhere more apparent than 

 in Paris. The most opulent families of France con- 

 gregate there, and, as they select certain quarters of 

 the town for their residence, the facts brought out in 



1 Journal of the Royal Agricultural Society, 1865, p. 270. 



