324 EK. J. ALLEN AND E. W. SEXTON. 
Reds. Constitution. Number. 
Pure Red Cc RR 1 
Red carrying Albino ; CicskoR 2 
Albinos. 
Albino carrying Black cuca 1 
Albino carrying Red ecRR it 
Albino carrying Black and Red ChCe Dkk 2 
As a result of breeding tests, made either within the generation, or 
by crossing with known pure reds, all these classes have been proved 
to exist amongst the offspring of this generation, the actual numbers 
obtained for the blacks, reds and albinos being given on pp. 302, 317 and 
318 respectively. 
The results recorded in this section afford further proof of the fact set 
out in Section I that the imperfect albino eye behaves in inheritance in 
accordance with the theory formulated by Bateson and Punnett for coat- 
colour in mice, etc., which assumes in addition to the factors for the 
individual colours the existence of a factor (C), which must be present 
if the colour characters are to become visible. 
Experiments with the Original Stock (p. 287). 
The fact that the absence of coloured retinal pigment in the “ all- 
white ” perfect-eyed animals derived from red stock is a somatic character 
and not hereditary receives some slight support from further breeding 
experiments which were carried out with the original stock from which 
the animals came. These experiments give no indication that the 
abnormality is latent in the stock. 
The two all-white specimens had occurred in two succeeding broods 
from a pair of red-eyed animals (see former paper, p. 45), all the other 
ofispring of which were normal red-eyed animals. Two of these red- 
eyed offspring survived and 3 young (which reached maturity) were 
obtained by mating them together. These three were one male and two 
females, and their eyes, though distinctly red, were much paler in colour 
than usual, and in other ways not quite normal. The male mated 
with both the females. Altogether 21 young were obtained, all 
with normal bright red eyes, and from their matings 17 similar young 
were produced in the next generation. The 2 females were also mated 
with the male IT.B. (p. 284), a red carrying albino. One female (14.a.) 
had 29 normal red-eyed young, and the other (14.b.) had 30. Two pairs 
of these young were mated together ; the one pair had a brood of 17 
red, and 5 albino all of the usual imperfect form, and the other pair had 
