Unilateral Transmission 



four generations. There are other instances of what 

 is sometimes awkwardly called the unilateral trans- 

 mission of abnormal qualities. Edward Lambert, 

 born in 1717, is said to have been covered with 

 1 spines.' His children showed the same 

 peculiarity, which began to be manifest from 

 the sixth to the ninth month after birth. One 

 of his children grew up and handed on the 

 peculiarity to another generation. Indeed, it is 

 said to have persisted for five generations, and 

 in the males only unilateral transmission." 



In our view, these abnormalities are of such a 

 kind that they are only possible in connection 

 with the male organ ; in other words, they are 

 mutations of the first of the four kinds cited 

 above those which appear only in connection 

 with the male organ. 



It is a curious fact that the general rule in 

 nature seems to be that the male is ahead of the 

 female in the course of evolution. The sexes 

 may be alike at a given period in the life-history 

 of the species. Presently a mutation appears 

 which is confined to the male alone ; thus arises 

 the phenomenon of sexual dimorphism. The 

 next step in the evolution of the species is 

 frequently a mutation on the part of the female 

 which brings her once again into line with the 

 male, and so the sexual dimorphism disappears, 

 for a time at any rate, A good example of this 

 is furnished by the sparrows ; in the common 



