No. 512] 



NOTES AND LITERATURE 



497 



symbol standing for imaginary bodies; for such bodies, on this 

 assumption, may carry other characters that remain, even though 

 one be lost, and these other characters would still be subject to 

 Mendelian rules and be associated with the absence of a character. 



In the earlier work on mice and other forms the different 

 colors, Y, G, B, Ch, W, are represented as allelomorphic pairs. 

 Thus Y pairs with G, or G with B, or Y with Ch, etc. It follows, 

 that if these color determiners are carried by definite bodies, 

 these must always be the same kind of body or homologous 

 bodies; otherwise they would not stand in this relation to each 

 other. Thus a gray mouse paired with a chocolate would give a 

 gray mouse, GCh whose germ cells would give the pair^r. Two 

 such mice paired would give : 



G Ch 

 G Ch 

 GG G Ch 



1~G G, 2 G Ch, 1 Ch Ch 



Similarly for every other combination. As a matter of fact 

 gray by chocolate gives not only gray and chocolate but some 

 black mice in the second generation. The formulae fail to 

 explain this result. Bateson, who was one of the first to point 

 this out, was led therefore to a new formulation of the facts, and 

 Cuenot to still another. Their views will be given later. 



Another difficulty in connection with the inheritance of yel- 

 low was soon discovered by Cuenot. Yellow mice bred to yellow 

 give not only yellow, but other colors as well. This would occur, 

 of course, if the yellows were heterozygous. Thus YG by YCh 

 would give yellows (YY, YG, YCh) and grays (CG). Some of 

 the yellows should be YY, and two such paired should give only 

 yellows. Cuenot was unable to produce such pure yellows. He 

 therefore adopted a special explanation 'selective fertilization 

 for this case. His view will come up again later. 



A third complication arose in the case of dilute colors. In 

 certain experiments, that need not be given here in detail, 

 Cuenot found that the only assumption that would account for 

 the facts was that two other factors— a strengthening or enforc- 

 ing character (fonce) F, and a weakening or diluting factor 



