RELATIVE INFERTILITY OF FITTEST 



535 



manifold. There are probably, as Spencer maintained, auto- 

 matically working physiological and psychical factors which 

 lessen reproductivity as individuation increases. It may be that 

 hyper-nutrition, sexual vice, the frequent absence of love 

 marriages, operate in the same direction ; it seems difficult to 

 doubt that selfish celibacy and selfish non-maternity are in 

 part to blame ; and there are all sorts of possible factors down 



2 2 4 6 6 



Fig. 49. Diagram illustrating the relation between Reproduc- 

 tion AND Individuation (from " Evolution of Sex ") 



Let the perpendiculars above the line A B denote the increasing degree 

 of total individuation of a series of forms i, 2, 3, 4, 5, 6 (say Worm, 

 Fish, Frog, Bird, Man, Elephant). Similarly, let the perpendiculars 

 from the line C D represent the rate of multiplication of the same 

 forms. The curves joining the apices of the two sets of perpendiculars 

 indicate, by their inverted symmetry, the inverse ratio of individuation 

 and rate of multiplication. 



to the marriage of heiresses who are often the sole survivors 

 of a dwindling family. Dr. Ireland points to the significant 

 fact that some of the high castes of India (Brahmins and Rajputs) 

 who are most exclusive in their marriages do not show the usual 

 dwindling tendency, which may be correlated with the circum- 

 stance that they are mostly poor and abstemious. 



