224. MULTIPLE FACTORS 
itself does not change the triangular type,-as shown by 
the fact that both single recessives are triangular in 
type and are identical in appearance with the double 
dominant. Only where the two recessives occur in 
the same individual does the type change to round. 
Six families were bred from the F,, and gave the 
following counts: 
Triangular Round Ratio 
507 30 16.9:1 
146 4 36.5:1 
48 3 16.1:1 
179 9 19.9:1 
1743 72 24.2:1 
159 7 22.7:1 
Totals 2782 125 22.3:1 
Expected 2725 182 15.0:1 
The actual ratios range from 16:1 to 36.5:1, which 
exceed the expected ratio of 15:1. Nevertheless, the 
deficiency in the round class is probably due to the 
lower viability of the round-capsuled type, for in 
later cultures where the conditions were more 
favorable the expected 15:1 ratios are more nearly 
realized. That 15:1 is the true ratio is shown by 
tests that were applied to these F, plants. In Fig. 
54, the 16 classes (15:1) of F, individuals are repre- 
sented. Within each square is also given the genetic 
composition of the class. The letter “c” stands for 
one of the recessive factors, and the letter “d” for 
the other factor. Both of these recessive factors 
acting in conjunction produce theround capsules cedd. 
Beneath each figure is given the expected ratio for 
