COLOR AND COAT CHARACTERS. 37 



description should produce about equal numbers of colored and albino 

 young. 



Since all the young in the matings of table 44 died prematurely no 

 5 wild which were heterozygous in color could be used for experimenta- 

 tion; therefore albino guinea-pigs or guinea-pigs which were hetero- 

 zygous in color were mated to a number of the available f wild in order 

 to eventually produce a race of albino hybrids. Such matings have 

 been described in table 45, and the heterozygous colored young from 

 these matings enter as parents into tables 47 and 51. Table 47 records 

 the matings of two females, heterozygous in color, with albino guinea- 

 pig males. Each female proved her zygotic formula to be Cc, because 

 she produced both sorts of young. In all, 16 colored and 8 albino 

 young were born, the most probable expectation being 12 of each kind. 



Tables 48 and 49 record the remaining matings of the wild hybrid 

 females, from the | wild through the -^ wild, in which one parent was 

 heterozygous in the color factor and the other an albino. This class of 

 matings should produce approximately equal numbers of colored and 

 albino young. The summary of tables 47 to 49 is given in table 50 

 and shows that the total number of colored young (51) is only slightly 

 greater than the number of albino young (43). Segregation and 

 recombination of gametes evidently occur in accordance with the laws 

 of chance as in matings among ordinary guinea-pigs. 



HETEROZYGOUS COLORED ANIMALS MATED INTER SE. 



We have already alluded to the fact that the heterozygous colored 

 young born from | wild females (table 45) enter into tables 47 and 51. 

 The former table has been discussed. The rest of the | wild, which we 

 know to have been heterozygous, were mated to guinea-pig males 

 likewise heterozygous in the color factor (table 51). Both hybrids and 

 guinea-pigs should produce in equal numbers gametes with and gametes 

 without the color factor. The union of such gametes in these matings 

 should give an average of 3 colored to 1 albino young. The actual 

 results agree closely with theoretical expectation, for 10 colored animals 

 and 3 albinos were produced, whereas the most probable expectation is 

 a ratio of 9 : 4 or 10 : 3. 



Since the more intense wild-blooded hybrids agree with the guinea- 

 pig in this class as well as in most other classes of matings, the remaining 

 more dilute-blooded hybrids may be considered in one group. The 

 I wild, tV wild, and ^sr "^^ females which were heterozygous in the 

 color factor and which were mated to guinea-pigs of similar zygotic 

 formula are recorded in tables 52 to 54. The summary of tables 51 

 to 54 is given in table 55. The total number of young from the matings 

 of hybrids, heterozygous in color, with guinea-pigs of the same char- 

 acter, was 119, of which 80 were colored and 39 were albinos. There 

 is here an excess of the recessive class, for the most probable expectation 



