26 GENETICS AND EUGENICS 



reaching this theory was inductive and beyond criticism. He 

 first collected all the facts obtainable about inheritance and 

 then attempted to frame an hypothesis which would account 

 for them all, which would bring them all under one point of 

 view. Where he erred was in accepting as facts some things 

 which we know are not facts. In fitting a theory to them, he 

 framed a false theory, simply because the assumed facts were 

 false. 



Darwin's cousin, Francis Galton, showed the unsoundness 

 of pangenesis by a simple experiment. He reasoned thus. If, 

 as Darwin assumes, gemmules circulating in the blood deter- 

 mine the character of the germ-cells, then blood of one animal 

 transfused into blood-vessels of another should carry into the 

 germ-cells of the second animal gemmules derived from the 

 first animal. Consequently offspring subsequently produced 

 by an animal into which blood has been transfused should 

 show characteristics of the animal from which the blood was 

 taken. Galton performed this experiment on rabbits but with 

 results wholly negative. The experiment, however, cannot be 

 regarded as altogether conclusive because (1) blood trans- 

 fused from one individual to another probably does not long 

 persist, but is replaced by new blood formed by the individual 

 into which transfusion occurred. Therefore the effects of 

 transfusion would at most be of short duration. (2) Suppos- 

 ing that modifications were induced in the germ-cells by 

 transfusion, it is not to be expected, in the light of our present 

 knowledge, that such modifications would in all cases appear 

 in the first generation offspring, but rather in the second or 

 later generations of offspring, but Galton did not carry the 

 experiment so far. Galton's experiment therefore cannot be 

 regarded as a complete refutation of pangenesis, but such a 

 refutation has become unnecessary through the development 

 of biological knowledge along other lines. 



The theory of pangenesis was an attempt to explain the 

 mechanism of the inheritance of acquired characters. If 

 acquired characters are not inherited, as we now have reason 

 to think, the hypothesis of pangenesis is unnecessary and 



