COAT CHARACTERS IN GUINEA-PIGS AND RABBITS. 



of such characters) , we should expect from the theoretical numerical 

 frequencies of classes (i) to (4) that pairs giving the four sorts of results 

 described would be as follows. The observed frequencies are for con- 

 venience in comparison given in a parallel column. 



The agreement between expected and observed frequencies, it will 

 be noticed, is as close as could reasonably be expected in so small a 

 number of pairs. 



Again, Darbishire mated dark-eyed animals, like those whose mat- 

 ings we have been discussing, with dark-eyed animals of different 

 parentage, one of the parents having been a hybrid, the other an albino. 

 In all such cases the albino parent evidently possessed and transmit- 

 ted to its offspring the dark-eyed character, for none of the pigmented 

 young were pink-eyed. But the hybrid parent, according to our hypoth- 

 esis, transmitted the pink-eyed character to half its offspring, forming 

 gametes as follows (see p. 48) : P d + P p Hr A \_d~\ + A [>]. 



Union of the gametes of the albino parent, all A [?], with gametes 

 like these would produce young as follows : 



Pd(A d) + Pd (A p} + A [dcf] + A {dp}. 



But as Darbishire utilized in the experiment under discussion only 

 pigmented animals, we are concerned at present only with the first two 

 classes of young. They are identical in character with individuals of 

 classes (3) and (i), respectively (p. 48), but occur in equal numbers, 

 whereas in a group of hybrids like that described on page 48, class 

 ( i ) is twice as abundant as class (3). 



The question now before us is, if individuals of classes (i) and 

 (3) be taken with equal frequency to mate with individuals taken at 

 random from a mixture of classes (i) to (4) in the proportions indi- 

 cated on page 48, what sorts of offspring are to be expected and in what 

 proportions in the various pairs formed. Making the calculations by 

 the methods already explained, we find that pairs should occur giving 

 the same four sorts of results as in the previous case (pp. 49 and 50, 1 

 to IV) ; but these pairs should occur in frequencies somewhat different. 



