RECAPITULATION 239 



The operation was perfectly successful in seven 

 specimens — that is to say, they recovered completely 

 and lived for many months, up to a year or more, 

 afterwards, but none of them became pregnant. 

 When killed no trace of ovary was found in any of 

 them ; in every case it had been completely absorbed, 

 and the uteri and vagina were diminished in size, and 

 anaemic. For grafting I used ovaries from young 

 rabbits of various ages, from seven days to six 

 weeks or more, but all were equally unsuccessful. 

 Satisfactory evidence by direct experiment of the 

 inheritance of somatogenic modifications due to 

 external stimuli cannot be said to have been yet 

 produced, and, as I have shown, such evidence from 

 the nature of the case must be very difficult to 

 obtain. The indirect evidence, however, which has 

 been considered in this volume is too strong to be 

 ignored — namely, the case of Japanese long-tailed 

 fowls, that of colour on the lower sides of Flat-fishes, 

 and the similarity of the congenital development 

 of the antlers in stags, to the generally admitted 

 effects of mechanical stimulation and injury on the 

 skin and superficial bones of Mammals. 



The general conclusions which are logically to be 

 drawn from our present knowledge with regard to 

 the problems of heredity and evolution in animals 

 are in my opinion as follows : — 



1. All attempts to explain adaptation by gameto- 

 genic mutations, or changes in gametic factors or 

 ' genes,' have completely failed, as Bateson himself 

 has admitted. 



2. The facts discovered concerning mutations and 

 Mendelian heredity harmonise ^vith the nature of tlic 

 majority of specific and varietal characters, and with 



