HEREDITARY TRANSMISSION AND VARIATION. 103 



friend Mr. Tegetineier, a great authority in these 

 matters ; by means of which, if you examine them 

 by-and-by, you will be able to see the enormous dif- 

 ference in their bony structures. 



I had the privilege, some time ago, of access to 

 some important MSS. of Mr. Darwin, who, I may tell 

 you, has taken very great pains and spent much 

 valuable time and attention on the investigation of 

 these variations, and getting together all the facts 

 that bear upon them. I obtained from these MSS. 

 the following summary of the differences between the 

 domestic breeds of pigeons ; that is to say, a notifi- 

 cation of the various points in which their organiza- 

 tion differs. In the first place, the back of the skull 

 may differ a good deal, and the development of the 

 bones of the face may vary a great deal ; the back 

 varies a good deal; the shape of the lower jaw varies; 

 the tongue varies very greatly, not only in correlation 

 to the length and size of the beak, but it seems 

 also to have a kind of independent variation of its 

 own. Then the amount of naked skin round the eyes, 

 and at the base of the beak, may vary enormously; so 

 may the length of the eyelids, the shape of the nostrils, 

 and the length of the neck. I have already noticed the 

 habit of blowing out the gullet, so remarkable in the 

 Pouter, and comparatively so in the others. There are 

 great differences, too, in the size of the female and the 

 male, the shape of the body, the number and width of 

 the processes of the ribs, the development of the ribs, 

 and the size, shape, and development of the breastbone. 

 We may notice, too, — and I mention the fact because 



