112 A NEW THEORY OF EVOLUTION. 



But even if polydactylism be a specific 

 variation and hereditary, it would not sup- 

 port the theory that new species arise by 

 the accumulation of small beneficial differ- 

 ences ; for neither polydactylism nor any 

 other recorded deviation from a normal type 

 arises by accumulation, or is of a beneficial 

 character, or of any advantage to its possessor 

 in the struggle for existence. 



Mr Bateson, in his exhaustive work ' Ma- 

 terials for the Study of Evolution/ has cata- 

 logued many deviations from normal types ; 

 but after examining the illustrations, we 

 cannot help coming to the conclusion that 

 the deviations are all of the nature of 

 accidents in the growth of the foetus, 

 monstrosities that arise and disappear with 

 the individual. 



Deviations are therefore no evidence of 



polydactylism in the father's family for four, nor in the 

 mother's for three, generations. In his opinion they were 

 truthful, and did not seem to have any motive to be other- 

 wise. 



We have here, it may be assumed, the origin of a case of 

 polydactylism, and may infer that it was caused by some 

 accident to the foetus when two or three months old the 

 mother was not certain about the exact date. 



This case seems to suggest the possibility of modifying 

 type by an operation on the germ-plasm, and as polydactylism 

 is hereditary, it is possible that if a germ-plasm could be 

 modified, the resulting specific variation might be hereditary, 

 J. W. B. 



