130 
JOUENAL OF MAMMALOGY 
ALBINO 
From this wild type distinct graded losses of pigment have taken place, 
the extreme of which is complete albinism, or entire absence of pigment, 
leaving the fur clear white and the eyes pink. The pinkness of the 
eye is due to the absence of pigment in the iris, which is typically colored 
by black or brown pigment granules, so that the blood in the capillaries 
on the retina is directly visible. This variation is to be sharply dis- 
tinguished from “partial albinism,’’ a term which has been apphed, 
unwisely it now appears, to the occurrence of white spotting in animals 
whose eyes retain their full color. The color of the eyes is an important 
point of distinction between complete albinos and spotted animals. 
Cases of true albinism have been reported in nearly all the famihes of 
rodents. Data from only five of the commonest famihes are given 
here, the famihes being hsted roughly in the order of their relationship 
from the more primitive to the more speciahzed.^ 
. Leporidce — Oryctolagus cuniculus — European “rabbit.” 
Sciuridce — *Marmota monax — ^Woodchuck. 
*Scmrus hudsonicus — Northern red squirrel.^ 
*Sciurus carolinensis leucotis — American gray squirrel. 
*Tamias striatus lysteri — Chipmunk, 
Muridce — Mus musculus — House mouse. 
Rattus norvegicus — Common rat. 
*Microtus pennsylvanicus — Meadow vole. 
*Fiber zibethicus — Muskrat. 
Peromyscus leucopus noveboracensis — Deer mouse. 
HystricidoB — *Erethizon dorsatum — Canada porcupine. 
Caviidce — Cavia cobaya — Guinea-pig. 
The inheritance of the albinism has been studied in the rabbit, the 
house mouse, the house rat, the deer mouse and the guinea-pig. In all 
of these it is due to a gene which acts as a Mendehan recessive to full 
color. At the same (albino) locus in the germ plasm have occurred 
other mutations. In the rat, a change in this locus has produced both 
3 1 have followed the older order of classification which includes the Leporidse 
in the Rodentia. 
^ Through the kindness of Professor Barrows of the Michigan Agricultural 
College and Prof. W. E. Castle of Harvard University the writer has learned of 
the capture of a pair of albino red squirrels by A. E. Secord, of Wheeler, Michi- 
gan. Breeding experiments to test the inheritancje of this variation were to have 
been attempted but expense and pressure of other work have prevented the writer 
from undertaking the project. At last reports the squirrels were alive and for 
sale and it is hoped that they will come into possession of some interested person. 
