114 Mr. G. P. Mudge. On the Hereditary | May 8, 
These “Irish” members, combined with the similar offspring of other 
crosses, have been already considered (supra, p. 102). 
In experiment 45, the same self-black rat was crossed with an albino which 
had been extracted from a cross of Cr2xCr4 (éxperiment 71). The Cr 2 
was derived from a cross of a wild grey x albino. 
In experiment 46, a very similar cross was made, but the self-black member 
was extracted from across between two “ Irish” 6 individuals (experiment 50). 
The albino used in this mating (experiment 46) was sister to that used in 
experiment 45. We may, therefore, consider experiments 45 and 46. 
together. The offspring will depend upon the nature of the Cr 4 parent. It 
will be assumed that the self-black parent in each case is homozygote, and in 
fact that used in experiment 45 has been proved to be so, by the previous 
results of 43 and 44. 
Albinoes extracted from a cross of Cr 2 x Cr 4, may be expected to include 
individuals of the following zygotic characters: cgBsP, cgBSsP, eGgBsP, and. 
cGgBSsP (supra, p. 111). If the albino is cGeBsP, and it is crossed with a 
homozygote Cr 7, the prediction (Table II, p. 109) is :— 
1 Cr 2+1 Cr 6 8, 
If the albino is cGgBSsP, the prediction is :— 
SAN Ore VAT EOI ONG (2S Ore Gy ae 
In the two experiments (45 and 46) which we are considering, the total. 
offspring 1s :— 
11 Cr 2+8 Cr 6641 Cr 6a. 
In experiment 46 no Cr 6 a type appeared, and it therefore suggests that. 
the albino parent is cGeBsP, and probably differing from that in experl- 
ment 45, in the absence of 8. 
If, therefore, we take experiment 45 alone the result is :-— 
27Cr. 2-2 CrOuoe laCribea, 
This is as near as it is possible to get to expectation with the odd numbers 
obtained. The presence of grey offspring in both experiments is conclusive 
proof that the two albinoes carried the grey determiner. 
Thus in this case, prediction as to the nature of the Cr 2, of the two. 
extracted Cr 4 individuals, and of the two Cr 7* individuals, is tentatively 
fulfilled. 
The behaviour of the black individual in the manner described, in 
experiments 43, 44, and 45, shows in a marked manner the influence which 
the albino parent exerts upon the nature of the offspring. In experiments 43. 
* One of these two (ie, that of experiment 45) is the same individual as that. 
considered on p. 110. | 
