1871.] Mr. F. Galton's Experiments in Pangenesis. 



409 



At the end of all, the vein was tied. It was, no doubt, the surest plan 

 to avoid future hemorrhage, especially as the blood was defibrinized ; 

 but the rabbits were apt to suffer from phlebitis, and I lost some thereby. 



Owing to the extreme rapidity and stiffness of the coagulation of 

 rabbit's blood, it is quite easy to estimate the quantity that may have 

 been spilt on the operating-table. It has simply to be sponged into a 

 measuring-glass. 



Cross- circulation would be a very easy operation in animals whose 

 carotids were even a trifle larger than those of silver-grey rabbits ; but it 

 is difficult with these, because the smallest canula which can be used with 

 propriety can only just be forced into the largest of them. It is no use 

 operating with small canulse ; in every case, a layer of fibrine is sure to 

 line the tube ; if the bore is small this layer chokes it, while a layer of 

 equal thickness in a larger tube leaves a free central passage. I found 

 canulse inch in diameter of bore were worthless ; those I used were 



inch. If I were to operate again, I should not use silver-grey rabbits, 

 on account of their smallness, but "Belgian hare" rabbits. When the 

 canulse are brought home together, the wire hooks, shown in the sketch, 

 secure them; but I also slipped an India-rubber band over the tips of their 

 handles. The cut ends of the artery were held open and stretched out by 

 a pair of delicate curved forceps (a suggestion due to Dr. Murie), and the 



canula was pressed in (the shape of its mouth was the result of many 

 trials and modifications), and a ligature was put on. In the diagram, A 

 represents one pair of canulse, both opened and closed. B shows their 

 position at the time of crossed circulation. It will be observed that each 

 artery requires four pieces of apparatus, viz. two spring forceps to stop the 

 blood, and two canulse. Thus, when the throats were brought close toge- 

 ther, to connect the arteries cross-wise, there were no less than eight 



