PUTORIUS ERMINEA. 
63 
Adirondack region only, for I have not seen it elsewhere during the 
transition. It has been my experience, and the experience of the 
many hunters and trappers that I have consulted on this point (an 
experience resulting from the examination of upwards of an hundred 
specimens caught at about the time of the first snow) that the Ermine 
never assumes the white coat till after the ground is covered with 
snow, which is generally late in October or early in November. It 
frequently happens that the temperature of the atmosphere is many 
degrees lower during the week or ten days preceding the first fall of 
snow than at, or immediately subsequent to, the time of its deposi- 
tion. Notwithstanding these facts, it is equally true that Ermine 
caught up to the very day of the first appearance of snow bear 
no evidence of the impending change. Within forty-eight hours, 
however, after the occurrence of this snow-storm (provided enough 
has fallen to remain and cover the ground; and regardless of the 
temperature,, which commonly rises several degrees soon after the 
storm sets in) the coat of the Ermine has already commenced to 
assume a pied and mottled appearance (often symmetrically marked 
and strikingly handsome), and the change now commenced pro- 
gresses to its termination with great rapidity. In early spring, the 
period for the reversal of this process, the changing back from the 
white coat of winter to the brown summer coat is determined by the 
same cause — -the presence or absence of snow. 
It may be asked “ what induces the change in individuals kept in 
confinement?" My reply is: certainly not temperature, for it has 
taken place when the animal was caged in a warm room, indoors. 
The transition is more tardy in confinement than in a state of nature, 
and may be coincident with the moult. In any case, we find the ex- 
planation of its occurrence in the inevitable influence of hereditary 
habit; and it is not rational to suppose that the temporary effect of 
different conditions of environment would, in a single season, nullify 
a tendency that is the outgrowth of causes that have been operating 
for ages to bring about and perpetuate certain fashions for the pro- 
