MENDEL'S DISCOVERY 187 



body of the parent, the germ was a recent dis- 

 covery. It was natural, therefore, that the fixed 

 starting-point in the inquirer's mind should be 

 the body, and that the problem of heredity should 

 present itself to him as the task of finding out how 

 its characters could get into the germ-cells which (so 

 he had recently discovered) it produced, and which 

 give rise to the next generation. 



There can be no doubt that that was the way 

 in which the problem presented itself to Darwin's 

 mind. His theory of Pangenesis is an answer to 

 the question. How do the characters of the parent 

 get into the germ-cells which it produces ? He 

 imagined that this was brought about by every cell 

 of the body giving off a particle which somehow 

 reached the germ-cells, so that each germ-cell con- 

 tained a representative particle from every cell of 

 the body which housed it. This theory would account 

 not only for the inheritance of so-called inborn 

 characters, but also for so-called acquired ones ; 

 because if a dog had its tail cut off, the tail would not 

 be represented in the germ-cells of the dog imless 

 the particles had left the tail before it had been 

 amputated. Pangenesis died, not because Galton's 

 experiments designed to test it had a negative 

 result, but because Weismann's writings efiected a 

 swinging round of biological opinion, through 180 

 degrees, to a statement of the problem of heredity 

 which was the diametric opposite to that which 

 had prevailed hitherto. The doctrine preached by 

 Weismann was that to start with the body and inquire 



