1871.] Mr. F. Galton's Experiments in Pangenesis. 397 



defibrinized blood, which I procured by whipping it up thoroughly with a 

 whisk of rice-straw ; and, in order to procure sufficient blood, I had on one 

 occasion to kill three rabbits. I alternately bled the silver-grey and in- 

 jected, until in some cases a total of more than 3 ounces had been taken 

 out and the same quantity, wholly defibrinized, had been thrown in. This 

 proportion corresponds to more than 6 lbs. of blood in the case of a man . 



(3) The third operation consisted in establishing a system of cross-cir- 

 culation between the carotid artery of a silver-grey and that of a common 

 rabbit. It was effected on the same principle as that described by 

 Addison and Morgan (Essay on Operation of Poisonous Agents upon the 

 Living Body. Longman & Co., 1829), but with more delicate apparatus 

 and for a much longer period. The rabbits were placed breast to breast, 

 in each other's arms, so that their throats could be brought close together. 

 A carotid of each was then exposed ; the circulation in each vessel was 

 temporarily stopped, above and below, by spring holders ; the vessels were 

 divided, and short canulae, whose bores were larger than the bore of the 

 artery in its normal state, were pressed into the mechanically distended 

 mouths of the arteries ; the canulse were connected cross-wise ; the four 

 spring holders were released, and the carotid of either animal poured its 

 blood direct into the other. The operation was complicated, owing to the 

 number of instruments employed ; but I suspended them from strings run- 

 ning over notched bars, with buttons as counterpoises, and so avoided en- 

 tanglement. These operations were exceedingly successful ; the pulse 

 bounded through the canulse with full force ; and though, in most cases, 

 it began to fall off after ten minutes or so, and I was obliged to replace the 

 holders, disconnect the canulse, extract the clot from inside them with a 

 miniature corkscrew, reconnect the canulse, and reestablish the cross-flow 

 two, three, or more times in the course of a single operation, yet on two 

 occasions the flow was uninterrupted from beginning to end. The buck 

 rabbit, which I indicate by the letter O, was 37| minutes in the most free 

 cross-circulation imaginable with his " blood-mate," a large yellow rabbit. 

 There is no mistaking the quality of the circulation in a bared artery ; for, 

 when the flow is perfectly free, the pulse throbs and bounds between the 

 finger and thumb with a rush, of which the pulse at the human wrist, felt 

 in the ordinary way, gives an imperfect conception. 



These, then, are the three sorts of operations which I have performed on 

 the rabbits ; it is convenient that I should distinguish them by letters. 

 I will therefore call the operation of simply bleeding once, and then 

 injecting, by the letter u ; that of repeated bleedings and repeated injec- 

 tions by the letter w ; and that of cross-circulation by the letter x. 



In none of these operations did I use any chemical means to determine 

 the degree to which the blood was changed ; for I did not venture to com- 

 promise my chances of success by so severe a measure ; but I adopted the 

 following method of calculation instead : — 



VOL. XIX. 2 II 



