268 THE CAUSATION OF DISEASE. 



It would, of course, be absurd to disregard altogether the influ- 

 ence of hereditary weakness, but I am convinced that, so far as 

 diseases of children are concerned, this plays a very subordinate 

 part, and that whatever weakness belongs to the new-born 

 infant is rather the result of ante-partem conditions of E (of 

 germ, sperm, and embryo). 



I have tested the truth of the above statements by a large 

 number of observations, and I could cite numerous cases where 

 weakly infants have, with judicious management, grown up 

 strong and vigorous, just as, on the other hand, I could give 

 a dismal list (as who indeed could not ?) of strong and 

 vigorous infants who, through faulty management, have grown 

 up into sickly, miserable specimens of humanity, if, indeed, 

 they have not been actually destroyed in their infancy or 

 childhood. 



Inasmuch as natural selection does not operate after pro- 

 creative life, it is important for us to answer the question : 

 When does the procreative period terminate ? Few women 

 bear children after two or three and forty ; in men, however, 

 the reproductive power may extend into extreme old age. 

 Nevertheless, the average age at which men cease to beget is 

 much less than that at which the power leaves them, seeing 

 that the wife becomes sterile a long time before the average 

 husband is physiologically impotent. If we place the average 

 age at which women cease to bear children at forty, and assume 

 the husband to be on an average three years older than his 

 wife, it will follow that the average age at which men cease to 

 procreate is forty-three. 



We may fittingly ask the question here, Is this limitation 

 to the natural procreative period of the man advantageous or 

 otherwise to the race ? I cannot but see in it one serious dis- 

 advantage, namely, that racial evolution is prevented from 

 taking place beyond this age. Whatever may be said of the 

 physical side of our being, it must be acknowledged that the 

 human mind is capable of much culture and improvement 

 after forty or thereabouts, but, as things are, gains in this 

 direction are lost to the race. It is, however, possible that 

 the same applies to the physical side also. Suppose, for 



