The Factor Hypothesis 63 



Considering first the C factor, one finds that a i :o ratio will result; 

 that is, all of the progeny will have the C factor. So far as C is 

 concerned, then, all of the progeny may be colored. 



Taking up now the R factor, it is evident that this will bring 

 a 3 : 1 ratio; that is, f of the progeny have both C and R and will 

 therefore be colored (whether red or purple will be decided later) ; 

 I have C but lack R and will therefore be colorless. The final 

 fate of this I is thus decided, and one need give no further atten- 

 tion to this group. The f , however, is eligible to be carried on 

 for further consideration under the P factor. 



The ratio produced by the P factor is 1:1; that is, ^ have P 

 and I lack it. So far as phenotypes are concerned, however, the 

 present fractionation applies only to the f that was carried over, 

 making | with and | without P. 



Summarizing, } have C but lack R and are therefore colorless; 

 I have C and R but lack P and are therefore red; | have C, R, and 

 P and are purple. The resulting phenotypic ratio is, therefore, 

 3 purple: 3 red: 2 white. 



PpRrCc ''selfed" (equivalent to PpRrCcXPpRrCc). 



Considering the C factor, the result is a 3 : i ratio, or | with and 

 \ without C. The latter group, \ is hereby dropped, since it 

 must be colorless, while the f is carried on for further con- 

 sideration. 



The R factor also gives a 3 : i ratio, or f with and \ without 

 R. But this fractionation applies only to the f that was carried 

 on. Therefore we have f Xf or A which has both C and R, and 

 f Xj or -i\- which has C but lacks R. This x\ is hereby dropped, 

 since it also must be colorless, while the 1^0 is carried on for further 

 consideration. 



The P factor gives 3:1, or f with and \ without P. This 

 fractionation applies to the iV which was carried on, so that we 

 have iVX 4 or H which has C, R, and P and is purple, and ^i Xi 

 or i;^ w^hich has C and R, but lacks P, and is therefore red. 



Summarizing, \ plus i'',; or (jv is colorless; ,m is red; and l\ 

 is purple. The phenotypic ratio, then, is 27 purple:9 red: 28 

 white. 



