304 



LEROY POWERS 



1.511883, whereas 9 plants did so (see Table 19.5). The same comparison 

 for the Bi to Ponderosa population is 0.65 expected and 3 obtained. Also, a 

 study of the tabulation below reveals that with an increased number of 

 gene pairs diflferentiating the parents the odds become even greater against 

 those plants which exceed 1.511883 being chance deviates. 



It remains to be seen whether plants of the Fi genotype plus plants of 

 genotypes which might have similar effects, but do not possess recombina- 

 tion of favorable genes in excess of the total number of favorable genes car- 



ried by the Fi, could be responsible for the results noted. The result would be 

 to increase the proportion of the F2 and Bi to Ponderosa populations fluctu- 

 ating around means very similar in magnitude to that of the Fi population. 

 The extreme case (but highly improbable) would be to have all of these two 

 populations made up of such plants. On this basis and on the basis that the 

 parents are differentiated by one pair of genes, the number of plants of the 

 F2 population expected to exceed 1.511883 is 1.36, and for the Bi to Pondero- 

 sa population is 1.30. The number of plants obtained (Table 19.5) is 9 for the 

 F2 population and 3 for the Bi to Ponderosa population. Furthermore, the 

 Bi to Porter population had 1 plant in a class beyond that in which any Fi 

 plants occurred. 



The analysis can be carried further. For the F2 population the number of 

 plants expected to exceed 1.562293 is 0.3223 and the number obtained is 3. 

 Whereas the values for the Bi to Ponderosa population are 0.3087 and 1, 

 respectively. Also, the frequency distributions (Table 19.5) in general do 

 not support the supposition that over one half of the plants of the F2 and Bi 

 to Ponderosa populations are fluctuating around a mean as great as that of 

 the Fi generation. Again with an increase in number of gene pairs differentiat- 

 ing the parents, the odds against the plants exceeding 1.562293 being chance 

 deviates become even greater. It is evident that the data are not in accord 

 with the assumption that plants of the Fi genotype have the greatest weight 

 per locule. This is true regardless of the number of gene pairs differentiating 

 the parents. Therefore, some of the plants falling in classes having values 



