32 Darbishire, Lazvs of Heredity. 



interest. Let us discuss it. When you ask the riddle 

 you do not say that you are not referring to individual 

 white and black sheep, but the man of whom the riddle 

 is asked invariably thinks that you are : in attempting to 

 answer it, the ideas that rush through his mind may 

 either take the form of seeking for some pun on the 

 words or perhaps for some humorous quotation in which 

 they appear ; and so forth : or, what usually happens, he 

 thinks that as a matter of fact a white individual does eat 

 more than a black, and (if he is a biologist) he may be 

 trying to think of some physiological explanation of the 

 fact, in connection possibly with the well-established 

 relation between pigmentation and the getting rid of 

 waste products. 



In the answer he is told that the amount eaten by 

 the sum-total of white sheep as compared with that eaten 

 by the sum-total of black sheep is the subject under 

 discussion ; and not any peculiarities of ingestion, diges- 

 tion, or egestion associated with whiteness as compared 

 with blackness. 



If the antithesis between truths about masses, and 

 truths about individuals which constitutes the point in this 

 riddle were more widely and more clearly perceived than 

 it is to-day, there would no longer be that confusion in 

 the minds of most biologists which prevents them 

 seeing the profound difference that exists between a 

 physiological Law like Mendel's, which is true of units, and 

 a statistical one like the Law of Ancestral Inheritance, 

 which is true of masses. All intending students of heredity 

 should be asked this riddle; and if they cannot detect the 

 fallacy in it they should be declared unfit for their intended 

 task. 



The similarity between the impression called into 

 existence in the mind by asking the question and Men- 



