50 HEREDITY AND SELECTION IN SOCIOLOGY 



The existence of the useless organ in itself need present no 

 danger ; but the maintenance of the determinants of that organ 

 after the determinate has ceased to have any value is very dis- 

 tinctly disadvantageous ; for these useless determinants absorb 

 nourishment, which is thereby subtracted from those deter- 

 minants which are of vital moment. Therefore, once natural 

 selection has ceased to interest itself — metaphorically speaking — 

 in the maintenance of an organ, the minus variations of that 

 organ will, sooner or later, necessarily outnumber the plus 

 variations ; and this in virtue of Nature's economy ; for the 

 supply of nutritive matter is limited in the germ-plasm as 

 elsewhere, and if the organ possesses no value for the species, 

 the maintenance of the determinants of that organ can only 

 be efiected at the expense of the other, the vitally important 

 elements of the germ-plasm. But this weakening of the vitally 

 important elements is harmful to the species, and must be 

 checked if the species is to persist. 



An important role in germinal selection is necessarily played 

 by amphimixis, and by the reduction of the chromosomes in the 

 germ-plasm during maturation. Take the case of an organ A, 

 and suppose an ascendant variation of this organ to occur, 

 having its origin in an accidental perturbation in the balance of 

 intragerminal nutrition. Instead of remaining a merely static 

 variation, as it was originally, the ascendance of the deter- 

 minants of A will soon acquire kinetic value, for these growing 

 determinants will soon begin to attract an ever-increasing 

 quantity of nutriment. The ultimate result of this alteration 

 in the nutritive balance will be a continual strengthening of 

 these determinants, so that the organ, or part of an organ, 

 determined by the latter will be altered. If this alteration attain 

 to selective value, then natural selection will either maintain 

 or eradicate it. If it do not attain to selective value, its main- 

 tenance or disappearance depends entirely on the balance of 

 forces within the germ-plasm. 



