76 PERPETUATION OF LIVING BEINGS 



markuble 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 si/.e 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 proportions 

 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, because 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 who may be pigeon fanciers, and 

 I wish you to understand that in approaching the subject, 

 I would speak with all humility and hesitation, as I regret 

 to say that I am not a pigeon fancier. I know it is a great 

 art and mystery, and a thing upon which a man must not 

 speak lightly ; but I shall endeavour, as far as my under- 

 standing goes, to give you a summary of the published 

 and unpublished information which I have gained from 

 Mr. Darwin. 



Among the enormous variety, I believe there are 

 somewhere about a hundred and fifty kinds of pigeons, 

 there are four kinds which may be selected as representing 

 the extremest divergences of one kind from another. 

 Their names are the Carrier, the Pouter, the Fantail, and 

 the Tumbler. In the large diagrams they are each 

 represented in their relative sizes to each other. 

 This lirst one is the Carrier ; you will notice this large 

 excrescence on its beak ; it has a comparatively 

 small head ; there is a bare space round the eyes ; it has 

 a long neck, a very long l.-enk, very strong legs, large feet, 

 long wings, and so on. The second one is the Pouter, a 

 very large bird, with very long legs and beak. It is called 

 the Touter because it is in the habit of causing its gullet 

 to swell up by inflating it with air. I should tell you 

 that all pigeons have a tendency to do this at times, but in 

 the Pouter it is carried to an enormous extent. The birds 

 appear to be quite proud of their power of swelling and 



