108 HEREDITY AND SELECTION IN SOCIOLOGY 



of consanguinity. Self-fertilisation difiers also from parthenogenesis, 

 since, unlike the latter, a steady diminution of the number of hetero- 

 geneous ids must be its result ; it is true, on the other hand, that both 

 self-fertilisation and parthenogenesis have an advantage, as compared 

 with consanguinity, in that they do not permit the introduction of un- 

 favourably affected ids into the germ-plasm. 



