350 Action of the Genetic Material 



which have to be explained: (1) the elementary dosage relations 

 involving the ci locus and the more or less normal alleles; (2) the 

 dominant ci^^' with the opposite type of dosage effect and its compound 

 with the others; (3) the position effect R( + ) and R(ci), again in 

 different combinations. The first group of facts seems to be not dif- 

 ferent from those discussed above for bobbed: relatively simple dosage 

 relations between the mutant loci and some end product responsible 

 for vein formation. 



The order of these dosage effects is (including the information 

 obtainable only at low temperature, when the "normal" isoalleles can 

 be distinguished from each other), beginning with the extremest effect, 

 as follows: 



1. ci/0 extreme absence of veins 



2. ci/ci considerable absence of veins 



3. ci'/ci considerable effect varying to normal (ci* = +') 



4. ci ci ci not completely normal 



5. ciVO small effect visible only at low temperature, otherwise + 



6. +^/0 still smaller effect at low temperature, otherwise + 



7. +'''/0 almost normal at low temperature, otherwise + 



8. ciVci' 1 



9. +V+'' r normal 

 10. +"'/+"' J 



Stern's own explanation has been changed somewhat in a more 

 recent publication (1948), which we shall follow without going into 

 the details of his former theory. He first assumes that genie action 

 takes place between the gene and a substrate. As three ci produce 

 more venation, the substrate must be present in excess of the amount 

 turned over by one or two ci. The product of the interaction between 

 genes and the substrate enters a chain of reactions which is positively 

 correlated with the sequence of developmental processes producing 

 venation. Stern thinks that these conclusions are independent of any 

 theory of genie action. Actually, the concept is identical with what we 

 called an effect produced by the stimulation of the kinetics of a 

 process, but it is couched in different language. Stern also mentions 

 the possibility that different alleles use different substrates and thus 

 produce qualitatively different products, and he finds no difficulty in 

 incorporating this into quantitatively arranged results. Thus far the 

 tenets and their interpretation fit into the general scheme which we 

 discussed before. 



However, Stern thinks that something new comes in when com- 

 binations of different alleles are considered. The intermediate effect 

 of these suggests a simple dosage relationship, each allele acting 



