10 



INHERITANCE OF COAT-PIGMENTS AND COAT-PATTERNS 



The evidence contained in tables 2 and 3 (pp. 35, 36), is presented in the form 

 of summaries only. To give an idea of the sources from which it was obtained, 

 a genealogy may be considered in detail (fig. i). 



Wild gray 



. " 



o Wild white 

 I 



IZ,W[BH] 

 I 



34, 



16, GI(WBH) 



\ 



f 141 

 3 142 

 f 143 



f 144 

 <f 145 

 3 146 

 6 147 



GI(W-B) 



GI(H) 



GJ(W-BH) 



G 



BI(W-H) 



GH(B) 



BH 



ventral white patch below the average size 

 a " " " n a 



larye -white ventral patch 

 gray self 



a,rqe white ventral patch 



FIG. 1. 



A wild gray female and a wild white male were trapped together. Nothing 



is known of their ancestry, but they were probably derived from escaped 



tame albinos which had mated with wild gray rats. This pair of captured 



rats produced gray Irish young, two of which (A\ and A 2 ), when mated with 



ordinary albinos, produced gray Irish young which bore, as recessive char- 



acters, total albinism, black pigmentation, and the hooded pattern. Two 



of these triple heterozygotes (934 and c?i6) were now mated together 



and produced a litter of seven young (141-147, fig. i), which were tested 



as to their gametic condition, with the results indicated in fig. i. Five of 



the 7 were gray pigmented and 2 black, but no two were alike in gametic 



character. Males 146 and 147 were mated with black hooded females and 



with albino females of black hooded parentage, producing nothing but hooded 



young. This result showed that they bore no coat-pattern except the hooded 



one, and were free from recessive albinism. 



The j'oung of 6^147 were all black pigmented, showing that animal to 

 be entirely homozygous, but some of the young of c?i46 were gray pig- 

 mented, some black pigmented, showing that he bore black pigmentation 

 as a recessive character, being otherwise homozygous. 



