E. H. J. Schuster 
3 
latent in it one will obtain a uniform yellow hybrid, for yellow dominates grey, 
uniformity piebaldncss, and colour-productiveness albinism. If such yellow hybrids 
are paired together and a sufficient number of young obtained they should be 
in the following proportion : 16 albinos, 9 piebald yellow, 27 uniform yellow, 
3 piebald grey, and 9 uniform grey: see Appendix II, p. 12. Eight of these 
64 mice would be pure, all of different constitutions, and there would be two of 
each of 12 different kinds of hybrids, four of 6 different kinds, and eight of 
one kind. Thus a reasonable degree of complication is obtained when only 
two colours are employed ; when more than two colours are introduced the compli- 
cation is largely increased. I have brought forward this example to explain my 
reasons for not examining in detail the occurrence of each of the various types of 
mice produced in my experiments. For in addition to the inherent difficulties of 
such an examination, I am in total ignorance as to colours latent in the original 
stock of white mice. 
Types of mice produced. 
Bateson ('03) gives a list of a number of types of Fancy mice with a statement 
of the colour of the actual pigments contained in each, and almost all the mice 
produced in these experiments can be referred to one or other of the groups in this 
list ; I cannot, however, guarantee that I have referred them rightly, as no 
microscopic examination of them has been made, so that the colour as it appears 
to the naked eye is the only basis of the classification. 
After the name of each colour is given the abbreviation employed as a symbol 
for it. In giving instances of Cuenot's theory, for the sake of uniformity I have 
used my own abbreviations and not those employed in his original paper. 
(1) Grey (G) (Cinnamon or Agouti) figure 4. 
(2) Golden agouti (GA). 
(3) Yellow (Y). In this are included both yellow and cream, as these shade 
insensibly into one another and form indeed a highly variable group of colours. 
Figures 5, 7, 8 represent three conditions of yellowness, but the lightest yellow 
of all obtained was almost completely white, with but the faintest suggestion of 
pigment. It had, however, perfectly black eyes like all the coloured mice 
produced. 
(4) Sooty Yellotu {SY). 
(5) Chocolate (Ch.) figure 6. 
(6) Chinchilla (Cc.) figure 2. I cannot find this anywhere on Bateson's list. 
In the best specimens it is a beautiful silvery grey in colour but it shades insensibly 
into the ordinary grey coat, figure 3 being one of the intermediate forms. Allen 
('04) records having obtained some light grey mice in crossing house mice with 
albinos, these may possibly have been of the same nature as my Chinchillas. His 
apparently died in childhood so that he had no opportunity of breeding from them. 
Intermediate forms between pairs of these colours did occur and are represented 
by the symbols of the two colours joined by a hyphen. Thus figure 1 represents 
1—2 
