Nov. 12. 1921 Genetic Behavior of Spelt Form in Crosses 



345 



The agreement between the proportions expected and those obtained 

 is very close indeed to the 7 to 8 to i ratio, and perhaps too close to be 

 ordinarily expected from such a small population. 



The analysis may be carried a step further. As shown above, the 

 plants which would show unstability in the F3 (groups C and D), were 

 expected to be of two different genotypes. One of them, containing the 

 S1S1S2S2 forms (group C), was expected to segregate in the 15 to i ratio, 

 while the other (group D), containing the S1S1S2S2 and S1S1S2S2 genotypes, 

 should segregate in the simple 3 to i monohybrid ratio. Apparently 

 the individuals belonging to each of these two groups are those analyzed 

 in Table VI. 



Table VI. — Analyses of unstable spelts of the F2 generation, series 12126a. Number of 

 individuals of the F^ generation produced from Fn plants of groups C and D, compared 

 with the theoretical expectation 



■p2 INDIVIDUALS APPARENTLY SEGREGATING IN THE 1 5 TO I RATIO (GROUP C, 81818252) 



F2 INDIVIDUALS APPARENTLY SEGREGATING IN THE 3 TO I RATIO (GROUP D, S1S1S2S2 



AND S1S182S2) 



Total Fa plants segregating in 15 to i ratio, obtained, 5. 

 Total F2 plants segregating in 15 to i ratio, calculated, 6.7. 

 Deviation, 1.7. 



Total F2 plants segregating in 3 to i ratio, obtained, 8. 

 Total F2 plants segregating in 3 to i ratio, calculated, 6.7. 

 Deviation, 1.3. 



The data in Table VI show that forms were obtained in the F2 some 

 of which segregated in the 15 to i and others in the 3 to i ratio as ex- 

 pected. The agreement to the theoretical numbers of the progeny of 

 each F2 plant is as close as can be expected with such small numbers, even 



