146 Darwin, and after Darwin. 



opportunity of coming into play), while the latter, 

 although a product of domestication, is a remarkably 

 constant variety, and one which differs very much 

 in size and colour from the parent species. Again, 

 instead of a single transfusion, there were several 

 transfusions performed at different times. Moreover, 

 we did not merely allow the blood of one rabbit 

 to flow into the veins of the other (whereby little 

 more than half the blood could be substituted) ; 

 but sacrificed three wild rabbits for refilling the 

 vascular system of each tame one on each occasion. 

 Even as thus improved, however, the experiment 

 yielded only negative results, which, therefore, we 

 never published. 



Subsequently I found that all this labour, both 

 on Mr. Galton's part and our own, was simply 

 thrown away not because it yielded only negative 

 results, but because it did not serve as a crucial 

 experiment at all. The material chosen was un- 

 serviceable for the purpose, inasmuch as rabbits, 

 even when crossed in the ordinary way, never throw 

 intermediate characters. Needless to say, had I been 

 aware of this fact before, I should never have re- 

 peated Mr. Galton's experiments -nor, indeed, would 

 he have originally performed them had he been aware 

 of it. So all this work goes for nothing. The research 

 must begin all over again with some other animals, 

 the varieties of which when crossed do throw inter- 

 mediate characters. 



Therefore I have this year made arrangements 

 for again repeating the experiments in question- 

 only, instead of rabbits, using well-marked varieties 

 of dogs. A renewed attack of illness, however, has 



