148 MODES OF RESEARCH IN GENETICS 



in very convenient form as follows {loc. cit., p. 

 490): 



"Let X = the proportional number of organisms 

 that are pure homozygotes (with re- 

 spect to all the characters considered) , 

 y — proportion that are heterozygotic 

 with respect to all the characters 

 considered, 

 s = the proportion that are mixed, 

 V = the proportion that have any heterozy- 

 gotic characters. 



Then, if n = the number of successive self- 

 fertilizations 

 and m = the number of pairs of characters, 



y = (i)"", (2) 



z = l-{x+y), (3) 



m 



V = 1 — X = ^ ^—. (4) 



With continued brother X sister mating the 

 present writer ^ has shown that the proportion of 

 homozygotes also increases, in the manner shown 

 in the following table. 



1 Pearl, R. "On the Results of Inbreeding a Mendelian Popu- 

 lation : A Correction and Extension of Previous Conclusions." Amer. 

 Nat, Vol. XLVIII, pp. 57-62, 1914. 



Since this was written a paper by Fish announcing an independent 

 working out of the same point has appeared (Amer. Nat., 1915). 



