PROD UCTIOX OF 1IEA T IN GLANDS. 843 
Waller 1 estimates it at 20,000 kilogrammetres, and Nicolls 2 at .34,000 
Idlogrammetres. 
The production of heat in glands.- ( Hands are the seat of active 
chemical changes, accompanied by a production of heat, but during 
activity their blood Bupply is augmented, and the increased temperature 
arising from this cause often masks the heat produced by the activity 
of the glands. 
The submaxillary gland is an instance in which the activity of the 
tissue is accompanied by a greatly increased blood flow. Ludwig and 
Spiess 3 found by the thermo-electric method that the submaxillary 
saliva of a dog was 1° to 1°'5 warmer than the blood in the carotid 
artery. Bernard i ligatured the blood vessels of the gland, and found that 
stimulation of the chorda tympani still produced a slight rise in temper- 
ature, whereas excitation of the sympathetic produced a slight fall. The 
temperature in degrees is not stated, but Bernard brings these observations 
forward as additional arguments in favour of frigorific nerves. Morat 5 
states that he has been able to confirm Bernard's results ; Heidenhain, 6 on 
the other hand, observed a rise in temperature when the sympathetic was 
stimulated. Becently, Bayliss and Hill 7 have carefully investigated 
the question of the formation of heat in salivary glands : they used both 
the thermo-electric method and Geissler's thermometers. Their results 
led them to the following conclusions :— The temperature of the gland 
and tissues around it is almost as high as that of the aortic blood ; the 
saliva is not warmer than the gland and tissues around the duct, and no 
formation of heat can be directly determined in the submaxillary gland 
by any known method of measuring variations in temperature. On 
stimulation of the chorda tympani, the temperature of the saliva never 
rose higher than the temperature of the aortic blood. Xo doubt the 
gland produces more heat (luring activity, but, on account of the small 
size of the gland, and the rapid circulation, the difference cannot be 
shown. 
The intestines and liver. — According to Bernard, 8 the blood coming 
from the intestines is raised in temperature during digestion, the tem- 
perature of the blood in the portal vein being two- or three-tenths of a 
degree warmer than that of the abdominal aorta. Bernard also found 
that the liver was the warmest organ in the body, that the blood of the 
hepatic vein was higher than that of the portal vein, and showed a still 
further increase during digestion. 
Stimulation of the splanchnic, or of the vagi nerves, produces no 
calorific or frigorific effect in the temperature of the liver. 9 
1 " Human Physiology," 1893, 2nd edition, p. 75. 
2 Journ. Physiol., Cambridge and London, 1896, vol. xx. p. 107. 
3 Sitzungsb. d. k. Akad. d. TVisscnsch., Wien, 1857, Bd. xxv. S. 5S4 ; Ludwig, Wien. 
med. Wchnsclir., 1860, Xos. 28 and 29. 
4 "Lecons sur la chaleur animale," 1876, p. 428. 
5 Arch, de physiol '. norm, etpath., Paris. 1893, tome xxv. p. 285. 
6 Stud. d. physiol. Inst, zu Brcslau, Leipzig, 1868, Bd. iv. 
7 Journ. Physiol., Cambridge and London, 1894, vol. xvi. p. 351. 
8 " Lecons sur la chaleur animale," 1876, p. 190. See also this article, p. 809; Braune, 
Virchow's Archiv, 1860, Bd. xix. S. 470, 491. 
9 Waymouth Reid, "Proc. Phys. Soc," Journ. Physiol., Cambridge and London, 1895, 
vol. xviii. 
