I4l' lock: studies in plant breeding 



\ <■! t nal linee which together with the ordinate at the mean 

 divide the area of the polygon into four equal parts) is 1-7. 



Now. if all the samples contained the same number of indi- 

 vidual^, and that number were the same as the average of 

 all the actual samples, i.e., 564, the theoretical probable error 

 would be 1*33, this being the distance from the mean beyond 

 which half the percentages may be expected to vary in the 

 case of a series of samples containing 564 individuals each, 

 taken at random from a mixture of two kinds of things in 

 equal numbers. 



The result actually obtained is so close to this that it 

 appears likely that the actual samples do really represent 

 random batches from a mixture of yellows and whites in 

 equal numbers. And this again implies the literal truth of 

 Mendel's law that an equal number of the germ cells of a 

 heterozygote bears one or the other member of the pair of 

 allelomorphs concerned — in this case yellow and white — clear 

 evidence as to the nature of the germ cells being afforded by 

 the process of crossing with the recessive form. 



Turning once more to the diagram, it may be pointed out 

 'hat the particular proportion of yellow and white grains 

 '4H-6: 53-4) exhibited by the F 2 plant of which the offspring 

 examined, appears to have no influence upon the propor- 

 tions shown by those offspring. 



<)u growing extracted dominants on a small scale it was 

 found that the homozygote (yellow x yellow) was of a dis- 

 tinctly deeper yellow colour' than the average heterozygote 

 form (yellow x white), which exhibited a blended character 

 intermediate between the two parental types which had 

 ni.u been exl racted. 



F4. 



/</ '"><> <)n«- further general ioh was grown for the pur- 



d- i-i mining the proportion in which the male germ 



oe|]l legregated. The pollen parents in this case were the 



ofbpring of yellow grains from several of the plants enume- 



