8o8 



ANIMAL HEAT. 



work in England and in the tropics raised his temperature 0*27 and 

 l'l respectively, and an increase varying from 0'l to 07 has been 

 observed after similar exertion by Speck, 1 Rumpf, 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 0'3 abo^e 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 : 



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 Rolleston 12 have failed to demonstrate the formation of heat 

 in nerve. 



1 Arch.f. exper. Path. u. Pharmakol., Leipzig, 1882, Bd. xv. 



2 Arch.f. d. yes. Physiol., Boim, 1884, 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, etpath., 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. 

 w Arch.f. Anat., Physiol. u. wissensch. Med., 1848, S. 158. 



11 Stud. d. physiol. Inst. zu, Brest au, Leipzig, 1868, Bd. iv. S. 250. 



12 Journ. Physiol., Cambridge arid London, 1890, vol. xi. p. 208. 



