A. D. Darbishire 
25 
(iii) WxA Ax A WxA Ax A 
{HxA)x(HxA) 
Offspring of third kind. 
It is evident that the amount of albino ancestry is largest in (iii), smaller in (ii), 
and smaller still in (i). The doctrine of the gametic purity asserts that a series 
of individuals having any of the pedigrees above represented should contain 
25 per cent, of albinos and 75 per cent, of coloured mice. The law of ancestral 
inheritance proclaims that the percentage of albinos will be greater in (ii) than 
in (i) and greater in (iii) than in (ii): which is -exactly what we find to be the case. 
The number of albinos produced by each kind of pair is seen at a glance in 
the following table. 
Origin of the hybrids 
mated 
Number of 
young 
Number of 
albinos 
Albinos per cent. 
{HxH)x{HxH) 
93 
10 
10-75 
{HxH)x{HxA) 
107 
20 
18-69 
{HxA)x{HxA) 
121 
30 
24-79 
The amount of whiteness in the various coloured individuals resulting from 
these unions, and the colour of their coats, may be gathered from Table E on 
p. 35. An interesting feature is the reappearance of lilac in the grandchildren of 
unions between hybrids and albinos, though this colour has been seen to be 
absent from the immediate progeny of such unions. 
Extracted Hybrids crossed with extracted Albinos. 
In the unions just described, hybrids of various kinds were paired together. 
By pairing such hybrids with extracted albinos we should, on the Mendelian view, 
produce equal numbers of albinos and of dark-eyed hybrids. Out of 91 young 
actually produced, 36 were albino ; this is not an impossible approximation to a 
Mendelian half, but it is so bad as to afford a strong suggestion that the ancestry 
of the albinos used has affected the result, and this suggestion is confirmed by the 
fact that six of the young produced have pink eyes, a phenomenon never observed 
when albinos of ancestry which does not contain waltzers are crossed with these 
hybrids. See Table F, p. 36. 
Offspring of Extracted Dominants. 
(a) Extracted Dominants paired together. 
Pink-eyed forms with colour in the coat have been paired together, but the 
results so far obtained are too few to be of great value. The whole number of 
young, obtained from seven unions, was 32 (see Table H, p. 37). The young were 
all pink-eyed, but one was completely albino. 
Bioraetiika in 4 
