398 Action of the Genetic Material 



amounts, or qualitatively different products, each with a range of 

 specificity, like esterases or adrenaline-like bases (quoted in III 5 C Z?). 



This discussion shows how difficult it is to find a simple explana- 

 tion for all types of plciotropy including that in multiple alleles, 

 though, in a general way, we seem to find at work all the different 

 features of genie action we have always encountered. One more 

 example will be added in order to show that our problem might 

 overlap a completely different one, pseudoallelism. I have repeatedly 

 cited multiple allelic series controlling more or less complicated pat- 

 tern differences, as in coccinellid beetles and in grasshoppers. I men- 

 tioned also that in grasshoppers well-known loci, influencing pattern, 

 are located in a small section of one chromosome (Nabours and 

 Stebbins, 1950). The suspicion thus arose that multiple alleles con- 

 trolling patterns belong to the group of pseudoalleles, meaning, in 

 Lewis' interpretation, different genes, derived by duplication; in our 

 interpretation, effects of chromosomal sections within which any 

 change produces an allelic and similar action. If a pattern effect is 

 involved, we may call it a pleiotropic action upon different parts of 

 an animal or plant and thus understand the result as a combination of 

 pleiotropy and pseudoallelism. If, as in the examples quoted, a pigment 

 pattern is the effect and ff the pigment is always the same, the prob- 

 lem discussed earlier for the flour moth enters: the competence or 

 non-competence of different cells for depositing the pigment, the 

 possibility of which is otherwise genetically present in all cells. 



Some examples in plants cover the situation just described, for 

 example, Stadler's (1946ff. ) R-r series in maize and the R series in 

 cotton. The latter (following Stephens' review, 1951a) involves antho- 

 cyanin, which is chemically always the same. This pigment may be 

 deposited at the base and periphery of the petals and in different 

 shades at each place; further, at different places on the vegetative 

 parts of the plant and also upon the anther. In the Asiatic cottons a 

 large series of multiple alleles is known, each of which controls a 

 definite pattern of pigmented parts. As in the other cases mentioned, 

 an orderly arrangement of the effects in one part (e.g., the base of 

 petals) does not parallel the order of grades for another point of the 

 pattern. Thus, while we can explain the pattern as such by the com- 

 petence of cell groups which is determined independently (including 

 inhibition of synthesis), and the grading of multiple allelic action as 

 such by features of the kinetics of anthocyanin synthesis, the dis- 

 orderliness of the different effects when listed simultaneously requires 

 another, independently determined developmental system for which we 



