An Introduction to a Biology 



do they fit in with one another ? These are questions which 

 " the general inquiring public " may be expected to ask 

 and to which the specially trained biologist may be expected 

 to supply an answer. 



It is the thesis of the present essay to demonstrate the 

 compatibility of Mendelian and biometric theory and to 

 account for their apparent antagonism. 



A few words as to the spirit and scope of this essay seem 

 to me to be necessary. There are two methods of scientific 

 criticism, if, indeed, one of them can be justly called scientific. 

 One arises from a determination to crush a theory, while 

 the other consists in the postponement of the attack until 

 every endeavour has been made to appreciate the exact 

 point of view of the upholders of that theory, and in a willing- 

 ness to put off the attack for ever if the theory should not 

 be found wanting after all. The most flagrant example of 

 the first kind of criticism, on which I can lay hands, flowed 

 from the pen of a writer who, after having misrepresented 

 the theory he was attacking by declaring that it was " an 

 essential part of the Mendelian hypothesis that the (so-called 

 " extracted ") recessive individual which is produced by 

 pairing two first crosses is in every respect similar to the 

 original pure recessive," 1 concludes with these words : " This 

 mouse is clearly not a pure dominant, because it produces 

 albinos ; it is not a dominant hybrid, because it has pink 

 eyes ; and it cannot be a recessive, because when paired with 

 an albino it produces some black-eyed forms." It is evident 

 from this quotation that the stimulus which actuated the 

 author was a desire to stultify and refute Mendelian theory 

 at all costs, and that he did not make the smallest attempt 

 to discover what Mendelian theory really was or to put 

 himself in the position of those who held it to be true. For 

 an example of the second form of criticism I suggest that 

 the reader may turn to the following pages ; in them I 

 shall do my best to discover the most essential character- 



1 A. D. Darbishire, Biometrika, Vol. 2, pp. 282-5. 

 K 145 



