MENDEL'S DISCOVERY 189 



are not formed afresh by each generation. When 

 the fertilised egg divides, some cells are at once set 

 apart to become the germ- cells of the organism into 

 which this fertilised egg develops. It is the body 

 which is formed afresh at each generation : the germ 

 plasm has existed since the dawn of life. The 

 reader will, of course, understand that this is not 

 a statement of fact, but a presentation of the 

 Weismannian doctrine. 



The relation between Mendelian theory and this 

 doctrine may be considered from two points of view. 

 In the first place, a general acceptance of Weismann's 

 way of stating the problem of heredity was neces- 

 sary before the significance of Mendel's observation 

 could be understood. In the second place, Mendel's 

 discovery was a confirmation and amplification of 

 Weismann's thesis. 



These two points will be dealt with separately. 

 The publication of Mendel's paper in 1865 was the 

 throwing of pearls before swine. The problem of 

 heredity, as it presented itself to those who were 

 interested in the matter at that time, was, as I have 

 already stated, to explain how the characters of an 

 organism got into the germ- cells which it produced. 

 To Mendel, on the other hand, the problem was so 

 obviously the converse of this — namely, the question 

 how the characters of an organism are represented 

 in the germ-cells which produce it, that he did not 

 stop to discuss the matter. Mendel was so sure that 

 this was the correct statement of the problem that 

 he made no defence of it, and proceeded at once to 



