The Mciidelian Inheritance of Certain Chemical Characters in Maize. 



17 



or of white starchy, or white sweet. But if nitrogen content, for 

 example, is a single, definite unit character which segregates without 

 regard to starchiness, sweetness, yellowness or whiteness, we should 

 expect that in each of the four F^ random samples, taken on the 

 only possible basis (that of external appearance) there would be some 

 kernels with high nitrogen content, and some with low. The numbers 

 of these two kinds of kernels in a random sample would be expected 

 to be in the normal Meudclian ratio. This, then is our problem, to 

 determine whether each of our four Fg random samples is made up 

 of kernels bearing dominant and recessive conditions of invisible 

 chemical characters in regular Mendelian proportions. 



A strong suggestion that something like this is the fact arises 

 from the general inspection of the data undertaken in the preceding 

 section. We noted throughout a definite tendency for the F2 kernels 

 to differ in certain regular ways from the pure parents. Do these 

 differences arise because of an independent segregation of the character 

 dealt with ? As has been said, it is obviously not possible to answer 

 this question by the direct method. We can, however, by an indirect 

 method presently to be developed get some light on the matter. 



The nature of the reasoning employed in this indirect method 

 may be most clearly set forth if the complete case for a single chemical 

 character be worked out in detail. Let us do this for the character 

 "crude fat". 



Suppose we let F denote "low fat" (the dominant character) and 

 i the "high fat" (the recessive). Then it is a matter of simple Mendelian 

 symbolism to show that if fat content segregates in Fo as an inde- 

 pendent unit character we should expect the following results; Y, 

 S, y, and s having the same significance as above (p. 5). 



A random sample of yellow starchy Fo corn would include 

 kernels of the following gametic constitutions in the proportions 



