374 Royal Society : — 



and kind aid given to me by Dr. Murie, at real inconvenience to him- 

 self, for he had Uttle leisure to spare. The whole of the operations of 

 transfusion into the jugular vein were performed by him, with the help 

 of Mr. Oscar Fraser, then Assistant Prosector, and now appointed 

 Osteologist to the Museum at Calcutta, I doing no more than pre- 

 paring the blood derived from the supply-animal, performing the 

 actual injection, and taking notes. The final series of operations, con- 

 sisting of cross-circulation between the carotid arteries of two varieties 

 of rabbits, took place after Dr. Murie had ceased to be Prosector. 

 They were performed by Mr. Oscar Fraser in a most skilful manner, 

 though he and I were still further indebted, on more than one occa- 

 sion, to Dr. Murie's advice and assistance. My part in this series 

 was limited to inserting and tying the canulae, to making the cross- 

 connexions, to recording the quality of the pulse through the exposed 

 arteries, and making the other necessary notes. 



The breed of rabbits which I endeavoured to mongrelize was the 

 " Silver-grey." I did so by infusing blood into their circulation, 

 which I had previously drawn from other sorts of rabbits, such as I 

 could, from time to time, most readily procure. I need hardly de- 

 scribe Silver-grey rabbits with minuteness. They are peculiar in 

 appearance, owing to the intimate mixture of black and grey hairs 

 with which they are covered. They are never blotched, except in the 

 one peculiar way I shall shortly describe; and they never have lop ears. 

 They are born quite black, and their hair begins to turn grey when a 

 few weeks old. The variations to which the breed is liable, and which 

 might at first be thought due to mongrelism, are white tips to the 

 nose and feet, and also a thin white streak down the forehead. 13ut 

 these variations lead to no uncertainty, especially as the white streak 

 lessens or disappears, and the white tips become less marked, as the 

 animal grows up. Another variation is much more peculiar: it is 

 the tendency of some breeds to throw " Himalayas," or white rabbits 

 with black tips. From first to last I have not been troubled with 

 white Himalayas ; but in one of the two breeds which I have used, 

 and which I keep carefully separated from each other, there is a ten- 

 dency to throw " sandy" Himalayas. One of these was born a few 

 days after I received the animals, before any operation had been made 

 upon them, and put me on my guard. A similar one has been born 

 since an operation. Bearing these few well-marked exceptions in 

 mind, the Silver-grey rabbit is excellently adapted for breeding-ex- 

 periments. If it is crossed with other rabbits, the offspring betray 

 mongrelism in the highest degree, because any blotch of white or of 

 colour, which is not " Himalayan," is almost certainly due to mon- 

 grelism ; and so also is any decided change in the shape of the ears. 



I shall speak in this memoir of litters connected with twenty 

 silver-gre\ rabbits, of which twelve are does and eight are bucks ; and 

 eighteen of them have been submitted to one or two of three sorts of 

 operations. These consisted of: — 



( 1 ) Moderate transfusion of partially defibrinized blood. The silver- 

 grey was bled as much as he could easily bear ; that was to about an 

 ounce, a quantity which bears the same proportion to the weight of 



