HOW ARCTIC ANIMALS TURN WHITE 
AtHoucH I have not the details of any one particular case 
before me, so many instances are chronicled in which the 
hair of human beings, under the influence of strong mental 
emotion due to terror or grief, has become suddenly 
blanched within a single night or some such period of 
time, that the occasional occurrence of such a phenomenon 
must apparently be accepted as a fact. Such a change is, 
of course, due to the bleaching of the pigment with which 
the hair is coloured, although we need not stop to inquire 
by what particular means this bleaching is accomplished ; 
all that concerns us on the present occasion being to know 
that the hair in man may turn white in this manner under 
abnormal circumstances. And there appears to be evidence 
that under equally abnormal conditions a similar change 
may take place suddenly in the hair of the lower animals. 
This is exemplified by the well-known experiment made 
considerably more than half a century ago by Sir John 
Richardson on an Arctic lemming—a small mouse-like 
rodent, which habitually turns white in winter, although 
dark-coloured in summer. In this instance the little 
animal was kept in a comparatively warm room till winter 
was well advanced, when it was suddenly exposed to a 
temperature of 30° below zero; a continued exposure to 
this and a still more intense degree of cold eventually 
resulted in its death, which. took place within three 
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