MILLEK — COAT COLOR OF MOLES 
165 
and their thickness is commonly less than their diameter. The space 
between discs is but slightly greater than the thickness of the disc. In 
the regions of constriction the form of the color masses becomes modified 
by a reversal of proportions and they become elongated to styliform 
proportions before being finally pinched out by loss of the medulla. 
Throughout the major portion of the hair the colored areas appear 
perfectly black. However, where they are thinned out by terminal 
or intervening constriction of the medulla the last ten or twelve be- 
come progressively less purely black until the terminal style appears 
dark umber brown. This appearance is less marked in the intermediate 
constrictions than in the terminal one and is nowhere revealed except 
by careful scrutiny. The proportion of these brownish areas is so small 
and the difference in color is so slight that the effect is entirely lost in 
viewing the pelt as a whole. 
The cortical part of the hair is glistening white and clears to almost 
complete transparence. Only at rare and irregular intervals is a slight 
rusty stain visible. The thickness of the cortex and its freedom from 
color are probably responsible for the silvery sheen of the mole^s fur. 
Hairs were cleared in carbol-xylol to reduce the effect of air bubbles 
in microscopic study. 
HAIR OF THE NESTLING MOLE 
In a nestling so young that the hair lies flat and is quite stiff, the 
color is identical with that of the fully adult animal. There is the same 
monochrome pattern of the pelt as a whole, and the same lack of pattern 
in the individual hair, except where constriction, obliterating the 
medulla, leaves but the silvery cortex. In the specimen at hand the 
hair is so short that there is but one of these constrictions, that at the 
base of the hair, instead of three or four as seen in the adult. There 
can be no question then that the hair is fresh and unabraded. There 
appears the same slight rusty stain in the cortex in about the same 
degree as in the adult. The color areas are indistinguishable from those 
of the adult. Where the pigment becomes thinned out at the constric- 
tions, the same umber brown is evident. It is a question then, so far 
as microscopic study of the normal mole is concerned, whether the color 
area carries a single pigment which is so darkly brown as to appear 
black or bears a black and a yellow pigment intimately commingled. 
Study of the hair with the oil immersion lens failed to disclose a com- 
mingling of individual granules of pigment of different colors. If 
JOtrKNAL OF MAMMALOGY, VOL. 2, NO. 3 
