198 THE MENDEL JOURNAL 



the object of his investigation was biologically valid." 

 The dominating and all-embracing object we should 

 bear in mind was to measure (quantitatively describe) 

 the variation of this so-called homogeneous material. 

 Since Dr. Pearl admits it is possible that this object may 

 have no validit}/ there is nothing to be gained by repeating 

 here those considerations which we gave for regarding his 

 biometrical methods (namely, mass measurements) as 

 wholly invalid for the purposes of the mvestigation. 



It was further contended that the somatic condition of 

 a character maj; be quite unreliable as a criterion of its 

 gametic behaviour in inheritance. Dr. Pearl now frankly 

 admits that it is so (p. 192). Having done this he has de- 

 stroyed altogether the foundation of ' ' Biometrics " as a valid 

 instrument for dealing with problems of inheritance. 

 For that which can alone measure somatic characters 

 cannot give valid conclusions on problems of inheritance 

 which depend upon gametic behaviour. 



With regard to our second criticism, that the material 

 investigated by Dr. Pearl was not homogeneous, he 

 has attempted no real answer to it. He says he " did 

 not use the term ' homogeneous ' in the fancier's sense " 

 (footnote, p. 192). But he does not tell us in what sense 

 he did use the word. It is not, it seems to us, any reply 

 at all, to say he could not see " just how the actual facts 

 regarding the past history of these fowls was to be told, 

 without describing them as a homogeneous race." But 

 this particular race of hens is either homogeneous in some 

 definite sense or it is not. If it is homogeneous, the first 

 canon of science requires the strict definition of the term 

 employed. And, if it is not homogeneous, then no matter 

 what the mconveniences, the use of the term is unjustified. 

 As a matter of fact, Dr. Pearl did describe the past history 

 of the birds without reference to this term when, in his 

 original memoir, he stated " that they had been carefully 

 and closely selected in their breeding for more than 

 twenty five years." This, surely, would have been sufficient 

 description of his material, and it would, by itself, have 

 been quite accurate, without the introduction of a term 

 which Dr. Pearl, under the light and stress of criticism, now 

 virtually admits has no meaning at all, in the context in 

 which he employed it. 



