MULTIPLE ALLELOMORPHS 217 



possible in a given locus. But if more than one 

 kind of change did take place in a locus, a series of 

 multiple allelomorphs would result. 



The abihty of the theory of multiple allelomorphs 

 (identical loci) to explain the peculiarities of so 

 many cases in such widely separated fields proves the 

 usefulness of the hypothesis. Although the theory 

 of complete Hnkage also will cover the numerical 

 results in these cases (and some of the simpler cases 

 cited may prove to fall under this head) there is the 

 very strong first-hand evidence that has just been 

 given that makes the theory of multiple allelomorphs 

 more probable than the former theory. It is im- 

 portant to recognize that there is this strong evidence 

 in favor of multiple allelomori^hs, quite aside from 

 special cases of complete linkage, for, as will be shown 

 in the next chapter, there are some far-reaching 

 consequences of the theory of multiple allelomorphs. 



A word may not be out of place here concerning 

 the relation of the theory of multii)le allelomorphs to 

 the question of the variability of factors. The fact 

 that more than one change may take place in the 

 material at a given locus must not be taken to 

 mean that the material is undergoing continuous 

 fluctuation, for such mutations occur rarely and 

 afterward loc^have as do other mutations. In only 

 one well established case, that of variegated corn, 

 do mutations appear frequently at a given locus. 

 But even in such a case the change can not properly 

 be said to be fluctuating, but is of a fixed nature, 

 and when it has once occurred the new factor 



