History of the Theory of Heredity. 53 



. 



Gait on' 8 Experiments. 



Besides these theoretical objections, we have the ex- 

 perimental disproof furnished by Galton. In order to 

 test the hypothesis this experimenter selected the silver- 

 gray rabbit a variety which has, in itself, little ten- 

 dency to vary, although it readily crosses with other 

 varieties, and breeding freely with them gives birth to 

 hybrid offspring. Into the bodies of eighteen of these 

 silver-gray rabbits he transfused the blood of other vari- 

 eties, in some cases replacing one half of the blood. From 

 the eighteen rabbits thus operated upon eighty-six young 

 were produced, and in no case did the offspring exhibit 

 any of the characteristics of the variety from which the 

 blood was taken, but all of the eighty-six were pure 

 silver gray. From these experiments Galton concludes 

 that "the doctrine of pangenesis, pure and simple, is 

 incorrect;" and I think we must agree with him that 

 this conclusion is justified by the results which he 

 reached, although I hope to show that it is possible to 

 restate the hypothesis in a form which is so modified as to 

 escape this objection. 



TJie Sexual Elements Perform Different Functions in 

 Heredity. 



There is another objection which seems to me to be 

 of almost equal weight, but which has never, so far 

 as I am aware, been pointed out. The early writers 

 upon heredity attributed certain functions to the male 

 cell and others to the ovum; but we now know that their 

 means of observation were so inadequate, and their 

 knowledge so limited, that their conclusions were of 

 little value, and that both ovists and spermists were 

 wide of the mark. The fact that they erroneously atthb- 



