MULTIPLICATION OF THE HUMAK RACE. 513 



deficiency of reproductive power among them may be reason- 

 ably attributed to the overtaxing of their brains — an over- 

 t axing which produces a serious reaction on the physique. 

 This diminution of reproductive power is not shown only by 

 the greater frequency of absolute sterility; nor is it shown 

 only in the earlier cessation of child-bearing; but it is also 

 shown in the very frequent inability of such women to suckle 

 their infants. In its full sense, the reproductive power means 

 the power to bear a well-developed infant and to supply that 

 infant with the natural food for the natural period. Most of 

 the flat-chested girls who survive their high-pressure educa- 

 tion, are incompetent to do this. Were their fertility mea- 

 sured by the number of children they could rear without 

 artificial aid, they would prove relatively very infertile. 



The cost of reproduction to males being so much less 

 than it is to females, the antagonism between Genesis and 

 Individuation is not often shown in men by suppression of 

 generative power consequent on unusual expenditure in 

 bodily action. Nevertheless, there are indications that this 

 results in extreme cases. We read that the ancient athletes 

 rarely had children; and among such of their modern repre- 

 sentatives as acrobats, an allied relation of cause and effect 

 is alleged. Indirectly this truth, or rather its converse, 

 appears to have been ascertained by those who train men 

 for feats of strength — they find it needful to insist on con- 

 tinence. 



Special proofs that in men great cerebral expenditure 

 diminishes or destroys generative power, are difficult to 

 obtain. It is, indeed, asserted that intense application to 

 mathematics, requiring as it does extreme concentration of 

 thought, is apt to have this result; and it is asserted, too, 

 that this result is produced by the excessive emotional ex- 

 citement of gambling. Then, again, it is a matter of common 

 remark how frequently men of unusual mental activity leave 

 no offspring. But facts of this kind admit of another inter- 

 pretation. The reaction of the brain on the body is so violent 

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