Hibernation 
A Remarkable Natural 
Phenomenon 
By 
GEORGE W. HARVEY 
ap the naturalist every thing in 
nature is of interest, but in this 
great realm are certain mys- 
teries or phenomena that are enigmatic 
or wholly unexplainable to the most 
erudite biologist and among these zoo- 
logical puzzles is hibernation, that 
condition of lethargy in’ which the 
functions of the body are mostly sus- 
pended for weeks and months at a time. 
How a warm-blooded animal used to 
the most stirring activites for eight or 
nine months of the year, like the bear, 
the marmot and the prairie dog, can 
retire to a den, and from an ordinary 
sleep, which it is at first, pass into a 
condition of torpor in which all the or- 
gans that have to do with digestion, 
assimilation, waste and excretion, ex- 
cept the lungs, suspend their functions 
and remain absolutely quiescent for a 
period of several months, is so far a 
sealed book to. science. 
In man and, all non-hibernating ani- 
mals the action of the body functions 
are continuous whether sleeping or 
waking. In fact the building and 
waste of tissue is more perfect during 
sleep than when active. The stomach 
digests the supper that we eat before 
retiring, the kidneys extract the neces- 
sary waste material from the blood; the 
villi of the intestines absorb pabulum 
for the nourishment of the body, and 
a general renovation and upbuilding of 
the individual goes on, but in the hiber- 
nating animal the functions of diges- 
tion, waste and repair are suspended 
until he awakens in the spring. 
BEAR, if sufficiently fat, begins to 
fast some weeks before he retires 
to winter quarters. I have killed a 
number of them three and four weeks 
before the hibernating time with their 
stomachs and_ intestines absolutely 
empty, and yet the food that they 
Page 713 
loved was abundant all about them. 
On the other hand, a bear that for 
some reason, as lack of food, disease or 
old age and poor or broken teeth, will 
eat up to the very day of denning, and 
that last meal will be found still in his 
stomach when he revives from his win- 
ter’s sleep the next March or April, as 
the spring happens to be early or late. 
I remember one old fellow that I 
killed in his den the last of March. He 
was what we called a cinnamon in that 
locality, that is he was yellow instead 
of brown. He was a very large male 
but poor and mangy. There was no 
gloss to his fur: His claws were broken 
and splintered into ragged stubs, and 
his teeth worn to the gums with some 
of them missing and others broken. 
His body was covered with great scars 
evidently the result of combat with one 
or more rivals whose teeth and claws 
had certainly done execution on his hide. 
’T was plain to be seen that this bear 
had had a struggle for existence before 
holing up for the winter, and when I 
opened him the last meal that he had 
eaten, perhaps the very day that he 
denned, was still in the stomach. 
I’ was made up of acorns, sugar pine 
nuts and berries, both service and 
elder. The intestines contained many 
worms and some fecal matter, while 
the bladder was comparatively empty. 
Out of the twenty-six bears that we 
killed that fall and winter this was the 
only one that had a full stomach after 
he had retired for the winter. A few 
had partial meals in their stomachs, 
but those in the pink of condition were 
without food in their stomachs, fecal 
matter in their intestines or urine in 
their bladders. 
When a bear retires to his den for 
the winter he is covered with a layer 
of fat varying from two to six inches 

A hibernating animal, the woodchuck 

in thickness. This is laid over the body 
beneath the skin like a garment and 
can be peeled off in one mass as I have 
done many times, leaving the carcass 
devoid of fat on the outside. 
HE body of a bear after the fat is 
removed is plump and full fleshed 
if killed in the late fall or early winter, 
soon after the beginning of hiberna- 
ton, but one killed after some months 
in the den will show one or two more 
inches of fat and that much less lean 
flesh, and the lean portion will be with- 
out tone, lax and flabby. The carcass 
stripped of its fat will be noticeably 
smaller than that of a bear of similar 
proportions killed in the fall or early 
winter. 
That there is a continual process of 
fatty degeneration going on in the 
hibernating animal while his winter 
sleep endures I am sure, and this 
change from the proteid or nitrogenous 
to adipose or carbonaceous tissue is a 
physiological transmutation of these 
elements. Nitrogen somehow becomes 
carbon in the bear’s economy while he 
is torpid, and this change of one kind 
of tissue into another has been proven 
in non-hibernating animals, as set forth 
in the widely celebrated experiments of 
Pettinkoffer and Voit. 
AKING these experiments as a 
basis I venture the opinion that in 
the formation of fat from the muscular 
or proteid tissue of the bear during 
hibernation lays the secret of his 
lethargy and months of torpor. Any 
one who has ever observed a bear in 
the midst of his period of hibernation 
for any considerable time as I have, 
must have noted the similarity of his 
stupor to that of a man completely 
under the influence of alcoholic liquor. 
(Continued on page 748) 
