A CRITICAL EXAMINATION 17 



Hagedoorns' ^ discussion of the results of Castle 

 and Phillips' - on piebald rats, Shull's ^ analysis of 

 the inheritance of capsule in Bursa bursa-pastoris, 

 and finally my own ^ studies on fecundity in fowls. 

 It should be clearly understood that the above 

 criticisms are in no wise directed against biometric 

 methods per se, as weapons of research in attack- 

 ing the problems of genetics. On the contrary, 

 as Galton perceived, statistical methods are in- 

 dispensable in this field. These methods are 

 indispensable, in this particular case, because a 

 multitude of separate and distinct causal factors 

 discretely distributed in respect of their action, 

 are concerned in the determination of the make-up 

 of the adult organism. Since the locus of action 

 of all of these factors is in each case the individual, 

 it is impossible, generally speaking, to study the 

 action of any one factor free of the influence of 



* Hagedoorn, A. L. and A. C. "Studies on Variation and Selec- 

 tion." Zeitschr. f. ind. Abst.- und Vererhungslehre, Bd. XI, pp. 145- 

 183, 1914. 



2 Castle, W. E., and Phillips, J. C. "Piebald Rats and Selection. 

 An Experimental Test of the Effectiveness of Selection and of the 

 Theory of Gametic Purity in Mendelian Crosses." Carnegie Insti- 

 tution Publication No. 195, pp. 1-56, 3 plates, 1914. 



^ Shull, G. H. "Duplicate Genes for Capsule-Form in Bursa 

 bursa-pastoris." Zeitschr. f. ind. Abst.- und Vererbungslehre, Bd. 

 XII, pp. 97-149, 1914. 



^ Pearl, R. "The Mode of Inheritance of Fecundity in the 

 Domestic Fowl." Jour. Exper. Zool, Vol. 13, pp. 153-268, 1912. 

 Cf. also earlier papers listed in the bibliography of the paper here 

 cited. 



