XI PHENOMENA OF ORGANIC NATURE 411 



ver might scarcely notice it, and yet every one of 

 her children has an approximation to the same 

 peculiarity to some extent. If you look at the 

 other extreme, too, the gravest diseases, such as 

 gout, scrofula, and consumption, may be handed 

 down with just the same certainty and persistence 

 as we noticed in the perpetuation of the bandy 

 legs of the Ancon sheep. 



However, these facts are best illustrated in 

 animals, and the extent of the variation, as is well 

 known, is very remarkable in dogs. For example, 

 there are some dogs very much smaller than others ; 

 indeed, the variation is so enormous that probably 

 the smallest dog would be about the size of the 

 head of the largest ; there are very great variations 

 in the structural forms not only of the skeleton 

 but also in the shape of the 'skull, and in the pro- 

 portions of the face and the disposition of the teeth. 



The Pointer, the Retriever, Bulldog, and the 

 Terrier differ very greatly, and yet there is every 

 reason to believe that every one of these races 

 has arisen from the same source, that all the 

 most important races have arisen by this selective 

 breeding from accidental variation. 



A still more striking case of what may be done 

 by selective breeding, and it is a better case, be- 

 cause there is no chance of that partial infusion of 

 error to which I alluded, has been studied very 

 carefully by Mr. Darwin, the case of the domestic 

 pigeons. I dare say there may be some among you 



