So8 
ANIMAL HEAT. 
work in England and in the tropics raised his temperature o, 27 and 
1° - 1 respectively, and an increase varying from 0°1 to o, 7 has been 
observed after similar exertion by Speck, 1 Kumpf, 2 and Gley 3 ; the 
temperature was taken in the rectum, axilla, or mouth. Clifford 
Allbutt, 4 however, in a long series of observations, found that mental 
work had no effect upon the temperature. 
Cavazzani 5 states that in the case of a man whose skull had been 
trephined over the right temporo-occipital region, a thermometer placed 
in the dura mater showed a rise of two-tenths of a degree during mental 
activity. A. Mosso 6 maintains that intense psychical processes may 
cause so much heat to be set free in the brain that its temperature may 
remain for some time 0°-2 to o- 3 above the temperature of the rectum. 
In a curarised dog the action of cocaine may produce a rise of as much 
as 4° in the temperature of the brain (37° to 41°). In man, Lombard 7 
found that mental activity caused a slight rise in the temperature of the 
head, especially in the occipital region. 
It is probable, however, that this local rise of temperature is not due, 
as Mosso believes, to very active combustion in the ganglion cells, but to 
vascular changes consequent upon the mental activity. Hill and 
Nabarro, 8 have shown that the blood from the venous sinuses of the 
skull is less venous in colour than that of the femoral vein, that the 
metabolism of the brain is very low, and that it is scarcely increased 
during an epileptic fit. The average differences between the gases 
in samples of blood from the carotid artery and from the torcular 
Herophili of dogs were as follows : — 
Normal. 
Toxic Fit. 
Clonic Fit. 
Art. 
Tore. 
Diff. 
Art. 
Tore. 
Diff. 
Art. 
Tore. 
Diff. 
Carbon dioxide 
Oxygen . 
40-86 
10-81 
4 4-71 
13-39 
+ 3-87 
-3-42 
44-98 
15-17 
49-04 
10-22 
+ 4-06 
-4-95 
30-59 
15-77 
33-58 
11-46 
+ 2-99 
-4-31 
It is probable, therefore, that the temperature of the brain is not 
perceptibly greater than that of the blood. The cerebral circulation 
changes passively with every alteration of the general arterial or venous 
blood pressure, 9 and this is apparently the explanation of Lombard and 
Mosso's results. Moreover, the experiments of Helmholtz, 10 Heiden- 
hain, 11 and Eolleston 12 have failed to demonstrate the formation of heat 
in nerve. 
1 Arch.f. c.rj/er. PatJi. u. Pharmacol., Leipzig, 1882, Bd. xv. 
2 Arch.f. d. gcs. Physiol., Bonn, 1S84, Bd. xxxiii. S. 601. 
3 Compt. rend. Soc. de biol., Paris, 1884, p. 265. 
4 Note communicated to the writer. 
5 Arch. ital. de biol., Turin, 1893, tome xviii. p. 328. 
6 Proc. Roy. Soc. London, 1892, vol. li. p. 83; "Die Temperature des Gehirns," 
Leipzig, 1894. 
7 Arch, de physiol. norm, ct path., Paris, 1868, tome i. p. 670. 
8 Journ. Physiol., Cambridge and London, 1895, vol. xviii. p. 218. 
9 Roy and Sherrington, ibid. , 1890, vol. xi. p. 85 ; Hill, ibid., 1895, vol. xviii. p. 15. 
10 Arch.f. Anat., Physiol, u. ivisscnsch. Med., 1848, S. 158. 
11 Stud. d. physiol. Inst, zu Breslau, Leipzig, 1868, Bd. iv. S. 250. 
12 Journ. Physiol., Cambridge and London, 1890, vol. xi. p. 208. 
