HI BERN A TION 7 9 7 
bat and dormouse the rise may be even more rapid, as shown by the following 
examples : ] — 
( = 17° when very quiet \ 
, , . -r> , , , , I =34° when awake and I Temperature of 
l>at — Kectal temperature-, ,. »,. . ! , r>0 - 
active, fifteen air = 10 '5. 
I minutes later > 
T = 13° -5 when asleep 
I = 35°*75 when aw 
J and active, one j air = 9° '5. 
-p. =35*75 when awake Temperature of 
Dormouse — ,, -\ , ,. Y K ^ 3 „ 
and active, one 
hour later J 
The rapid rise in temperature is accompanied by a marked quickening of 
the respiration and of the heart-beat, and by active movements of the body. 
In some cases, especially in the marmot, there is a convulsive shaking of the 
body. The increase in the muscular activity appears to be the chief cause of 
the increased production of heat, although Horvath 2 and Dubois 3 do not 
accept this view. It is' to be noted, however, that Horvath draws attention to 
the increased respiration and heart-beat, and remarks that when once the 
shivering movements of the marmot have commenced, nothing can prevent 
the animal from awaking, and its temperature from rising. Dubois considers 
that the liver plays the most important part, for he finds that extirpation of 
the ganglia of the solar plexus, or ligature of the portal vein, and of the 
inferior vena cava just above the liver, prevents the rapid rise of temperature 
observed in an awakening marmot. An examination, however, of the experi- 
ments made by Dubois shows that the influence of the nervous system is 
considerable, for the greater the motor paralysis the smaller was the rise in 
temperature. 4 Removal of the cerebral hemispheres does not prevent hiber- 
nation or the rise of temperature observed when the animal awakes. The 
latter phenomenon, however, is abolished by section of the spinal cord at the 
level of the fourth cervical vertebra. 
In the case of bats and dormice, Pembrey and Hale White have shown 
that the sudden rise in temperature, when the animal awakes, is accompanied 
by a greatly increased discharge of carbon dioxide. 
The causes of hibernation. — The cause generally assigned for hibernation 
is cold, but a more careful consideration of the facts long ago showed 
that cold could not be the sole cause of the phenomena. Most observers 
who have worked at the subject of hibernation have found that even 
severe cold will not cause an active animal to hibernate. Saissy 5 observed 
that a low temperature alone was ineffectual, but the continued effect of 
cold, and a limited amount of air for respiration, caused a marmot to pass 
into a typical hibernating condition even in summer. Mangili 6 found that 
torpid marmots and bats were awakened by exposure to severe cold, and that 
confined air would not cause hibernation. Valentin and Horvath 7 have 
recorded cases of marmots hibernating under normal conditions during 
summer ; the animals were very fat, and the torpid condition was in all 
respects similar to that in winter. Pallas states that if the hamster be buried 
four or five feet below ground in a confined space, it begins to hibernate. 8 
Dormice have been kept throughout the winter in a warm room (16°), and 
yet they hibernated, and were not aroused when the external temperature 
1 Pembrey and Hale White, loc. cit. 2 Loc. cit., pp. 170, 175. 
3 Compt. "rend. Soc. de biol., Paris, 1893, pp. 210, 235 ; 1894, pp. 36, 115. 
* Ibid., 1893, p. 156. 
5 "Recherches experimentales anatomiques," etc., 1808. 
6 Arch. f. d. Physiol., Halle, 1808, Bd. viii. S. 433, 437, 444. 
7 Verhandl. d. phys.-med. Gesellsch. in Wiirzburg, 1881, Bd. xv. S. 209. 
8 See also Paul Bert, "Lecons sur la physiol. comp. de la respiration," Paris, 1870, 
p. 508. 
