1 82 GENETICS 



size and changes the form of the wing, has two other alleles, 

 antlered and strap, giving wings of other forms and sizes. 



Garnet: At the locus I, 44.4 are several alleles which 

 change the color of the eye in diverse ways. Some of these 

 are known as garnet, salmon, garnet 2, garnet 3. 



Pink: The eye colors, pink, peach, pink 3, pink 4, pink 5, 

 are a series of alleles located at III, 48.0. 



Series of alleles are known also in other organisms. Thus 

 in the rodents (rats, guinea pigs, rabbits), series of differ- 

 ent alleles are known, yielding different colors of the hairy 

 coat. In maize there are several allelic series modifying the 

 color of parts of the plant. Presumably any gene may, by 

 successive modifications, produce a series of alleles. 



As mentioned in an earlier chapter, all the members of 

 an allelic series affect the same character or part of the 

 body, yielding different modifications of that character. Fur- 

 ther, they show certain peculiarities of inheritance as com- 

 pared with different genes that are not alleles. Since they 

 are all modifications of the same gene, only one of the 

 alleles can be present in a single chromosome, and for this 

 reason only one of them can be carried by a single gamete 

 (except in cases of non-disjunction). Further, only two 

 members of a given allelic series can be present in any 

 diploid individual or zygote. 



There are thus two types of diversities among genes. 

 ( I ) On the one hand there are the different genes occurring 

 at different loci in the chromosomes, the diverse genes, 

 shown on the maps (figure 38), affecting many diverse 

 characteristics. (2) On the other hand there are these dif- 

 ferent modifications of a single one of these genes — the 

 multiple alleles. 



6. Any given single character, inherited in the sex-linked 

 or the autosomal manner, is a product of the interaction 

 of many genes, located in different parts of the genetic 

 system. 



