368 Action of the Genetic Material 



facts in favor of such an assumption. In our work on intersexuality we 

 made much use of potencies of sex determiners, which at that time 

 were assumed to be identical with genie quantities. As I stated previ- 

 ously (I 2 C fi ee), it seems more probable now that the entire chro- 

 mosomes are involved in Lymantria and that the potencies may be 

 quantities of heterochromatin. The term "potency" should be used 

 in a completely descriptive fashion, not implying any particular notion 

 in regard to different constitutions of genie material, but meaning a 

 different strength of action because of some variable features of the 

 genie material, which might sometimes be the quantity of hetero- 

 chromatic sections, or else some unknown qualitative feature. The 

 action in question might be a difference in the kinetic processes of 

 the reaction chains, a difference in the quantity of end products, a 

 difference in the substrate utilization which leads to threshold differ- 

 ences, a difference in the time of reaching thresholds of action and, 

 sometimes, also a qualitative difference in the synthesis of a product 

 or in the activation of different enzyme systems. If the term "potency" 

 is used in this sense, it follows that different potencies of mutant loci 

 might act exactly like different dosages if they affect one and the 

 same type of action (e.g., quantity of an active substance). However, 

 ff different potencies of the same genie material act directly or indi- 

 rectly upon different processes of the types just enumerated, very 

 irregular consequences should be expected. It is only in the former 

 case that a conclusion in regard to potencies of genie action will be 

 justified, as is shown by the examples already mentioned. 



In the ci case in Drosophila, the two phenomena act in the same 

 direction, the dosages and the potencies of some alleles. This is 

 especially conspicuous in what Stern calls isoalleles. One of the conse- 

 quences of the type of genie action represented in the model (fig. 18) 

 is that any number of genie actions above the threshold for normalcy 

 are possible, a notion which was used frequently in my earlier writings 

 and which appears also in Stern's bobbed work. This is the real mean- 

 ing of isoalleles. They can best be detected in the hemizygous condi- 

 tion (and in temperature experiments) where actions near the thresh- 

 old of normalcy, fluctuating also below it, are expected. The potencies 

 thus discovered (see Stern's isoallele +^) turned out to be of the 

 orderly type, that is, acting like dosage and thus acting in different 

 combinations in an orderly and parallel way. 



Since such potency alleles or isoalleles are clearly a special type 

 of multiple alleles, namely, those acting near or above the threshold 

 for normalcy, and since the lowest isoalleles, like Stern's +^, may just 



