INHERITANCE OF THE "EYE" IN VI ON A 



These ratios point clearly to the following conclu- 

 sions : 



1. Types E and S differ from each other in two fac- 

 tors each of which exhibits the phenomenon of domi- 

 nance or partial dominance. 



2. Types H and S differ in one factor which shows 

 dominance. 



3. Types W and S differ in one factor which shows 

 dominance. 



4. Types E and H differ in one factor, the heterozy- 

 gote being- intermediate between the parental types. 



It is not difficult to formulate, in terms of the cus- 

 tomary hypothetical factors, an hypothesis that readily 

 explains these facts. In fact, I have been able to formu- 

 late four such hypotheses. In each of these a certain 

 set of factors is assumed, each factor being assumed to 

 have the power of producing a particular effect on the 

 color pattern of the seed coat. But such explanations 

 offer no suggestion as to the real nature and modus 

 operandi of these factors. Unfortunately we do not 

 know much concerning the complex chemical processes 

 that go forward in the living cell. But enough is known 

 to show that differences such as are exhibited by the 

 various color patterns here considered may be due to 

 some such cause as slight difference in the rate at which 

 some enzyme may be produced in the cells of the seed 

 coat. For instance, it is known that an enzyme may 

 cause certain sugars and chromogens to unite to form 

 a glucoside, thus removing the chromogen from the 

 sphere of action of an oxidizing enzyme that might con- 



