THE MUTATED GENE 97 



In a similar way, a considerable number of plants with known 

 genetic basis have been analyzed by Wheldale (Onslow), Robin- 

 son, Lawrence, Hagiwara, Shriner and Anderson, Sando, Milner 

 and Sherman, and Scott-Moncrieff (1936). They have been 

 reviewed by this last investigator. From all the available 

 material Scott-Moncrieff derives some general information 

 regarding flower-color variation: In some cases, the action of the 

 different genes is independent and additive; in others, an inter- 

 action is found or a dependence of the effect upon the pH. The 

 following list covers the majority of known types of gene action: 



A. Chemical Changes of Anthocyanin 



1. Oxidation of the aglycone (without sugar residue) at 3' or 3' and 5'. 



2. Oxidation and methylation at ibidem. 



3. Methylation of the aglycone at ibidem. 



4. Glycosidic change from 3 to 3-5 type. 



5. Acylation. 



B. Sap-pigment Production 



1. Anthoxanthin and anthocyanin. 



2. Yellow anthoxanthin background and interaction effects. 



3. Ivory anthoxanthin copigment interaction and copigment effects. 



4. General anthocyanin background and interaction effects. 



5. Specific anthocyanin background and interaction effects. 



C. Sap-pigment Regulation 



1. General intensification. 



2. General suppression. 



3. Local intensification. 



4. Local suppression. 



D. Plastid Pigment 



1. Production background effects. 



2. Inhibition. 



E. Localized Acid pH 



Table 11 shows a few examples of such actions. 



The problem is now to find the general rules that might be 

 deduced from such facts. We leave out of consideration here 

 the different interactions and localized effects, as these are prob- 

 lems of pattern formation and not directly concerned with genie 

 action; partly they are also problems of genie interaction to which 

 we shall return soon. One of the general results of such studies 



