Principles of Heredity 201 



VII. THE QUESTION OF ABSOLUTE PURITY OF GERM-CELLS. 



But let us go back to the cases of defective "purity' 

 and consider how the laws of ancestry stand in regard to 

 them. It appears from the facts almost certain that purity 

 may sometimes be wanting in a character which elsewhere 

 usually manifests it. 



Here we approach a question of greater theoretical 

 consequence to the right apprehension of the part borne 

 by Mendelian principles in the physiology of heredity. 

 We have to consider the question whether the purity of 

 the gametes in respect of one or other antagonistic character 

 is or is likely to be in case of any given character a 

 universal truth ? The answer is unquestionably No but 

 for reasons in which "ancestry" plays no part*. 



Hoping to interest English men of science in the 

 Mendelian discoveries I offered in November 1900 a paper 

 on this subject to " Nature." The article was of some 

 length and exceeded the space that the Editor could grant 

 without delay. I did not see my way to reduce it without 

 injury to clearness, and consequently it was returned to 

 me. At the time our own experiments were not ready for 

 publication and it seemed that all I had to say would 

 probably be common knowledge in the next few weeks, so 

 no further attempt at publication was made. 



In that article I discussed this particular question of 

 the absolute purity of the germ-cells, showing how, on 

 the analogy of other bud-variations, it is almost certain 

 that the germ-cells, even in respect to characters normally 

 Mendelian, may on occasion present the same mixture of 

 characters, whether apparently blended or mosaic, which 



* This discussion leaves "false hybridism" for separate con- 

 sideration. 



