370 Action of the Genetic Material 



normal order). The decisive information would then have to come 

 from multiple allelic action of position effects of visible rearrange- 

 ments, namely, by discovering some rule for the different actions of 

 different rearrangements, for example, whether they fit in an orderly 

 way in a series of multiple alleles of the respective mutant locus or 

 not. Some of the disconcerting results of Stern's ci experiments in the 

 presence of rearrangements may supply the clues. Potency of a 

 mutant locus is a descriptive fact which still has to be endowed with 

 a definite meaning that fits all cases. 



As I have pointed out, potency efi^ects and, implicitly, multiple 

 allelic effects may be dependent upon qualitatively or quantitatively 

 different genie action. In my old work (1916-1920) I had assumed that 

 genie action of multiple alleles is concerned with catalyzing reactions 

 of different speed resulting in production of active stuffs (hormones, 

 including all determining stuffs and enzymes ) in corresponding quanti- 

 ties. Haldane (1954) drew attention to a paper of his, written in 

 1920, in which he said that genes produce definite quantities of en- 

 zymes, and that members of a series of multiple alleles produce the 

 same enzyme in different quantities; this is essentially the same as my 

 view was at that time. But in view of the facts of present-day bio- 

 chemical genetics Haldane prefers a different idea now. He thinks 

 that different alleles make chemically different primary products, for 

 example, enzymes with the same prosthetic group attached to different 

 proteins. Their interaction in heterozygotes is a biochemical matter, 

 different in different organs. The different order of individual pleio- 

 tropic effects of a series of multiple alleles might, then, be due to 

 qualitatively different products of each allele, each with a range of 

 specificity, like esterases or adrenaline-like bases. 



I cannot help being very skeptical about this qualitative bio- 

 chemical approach to our problem. Even in the multiple allelic series 

 for metabolites (e.g., pigments) the facts point more in the direction 

 of quantitatively different actions, as Wright's work on pigmentation 

 in guinea pigs illustrates. Bonner's conclusions for Isleurospora (1951) 

 may again be cited. When it comes to series of morphological charac- 

 ters, I have great difficulty in visualizing the results in terms of quali- 

 tative specificities of the genie products. 



Therefore, we may end this discussion by presenting an example 

 which simultaneously studies dominance, dominance modifiers, and 

 multiple alleles in the same material in quantitative work, and which 

 permits showing that only a system of genie action involving the 



