532 EVOLUTION OF HEAT, LIGHT, AND ELECTRICITY. 



very much at different heights. In the ascent, as Lortet 1 observed, the in- 

 ternal temperature of the body fell during exercise, especially when the 

 stomach was empty, and the skin was freely perspiring to a degree, indeed, 

 that was almost proportional to the height ascended. When the feeling of 

 malaise, so often complained of by Alpine travellers, or mal de inontagne, 

 was most evident, the temperature was lowest, and the sensation was best 

 removed and the temperature raised by frequent ingestiou of food. The 

 observations of Clifford Allbutt 2 do not support the statements of Lortet, for 

 he found that with one or two exceptions the tendency of exercise in Alpine 

 climbing was to elevate the temperature. The forenoon rise occurred earlier, 

 and the evening fall had often reached the night-level at 9 P.M. The differ- 

 ence was probably owing to the different physique of the two observers. 

 Passive movement (swinging or rocking for fifteen minutes) was found by 

 Manasseiu 3 to lower the temperature of rabbits about 1 Fahr., even when 

 they were carefully protected from draught. The depression reached its 

 maximum half an hour after the swinging had ceased, and lasted for two 

 hours. The experiments of various observers, moreover, have shown that a 

 certain amount of heat is developed during the active contraction of muscu- 

 lar tissue, the rise in temperature of a muscle like the Biceps, after a few 

 powerful contractions, being as much as 1 Fahr.; and this increase in tem- 

 perature may be regarded as due to the increased energy of the chemical 

 changes, and in some measure also to the mechanical effects of friction, etc., 

 taking place in the contracting muscle. It is remarkable that voluntary in- 

 crease of the frequency and extent of the respiratory movements for the 

 space of ten minutes, or suspension of the respiration at the end of a full 

 inspiration, alike produce a decline in the temperature of the blood, as shown 

 by that of the skin over the radial artery ; in the former case amounting in 

 M. Lombard's 4 experiments to as much as 2 Fahr. Perhaps in this case, 

 as Drs. Wilson Philip, Hastings, and C. J. B. Williams have pointed out 

 takes place in the performance of artificial respiration, the cooling effect of 

 the air introduced is greater than the warming effect of the respiratory pro- 

 cesses to which it becomes subservient. Coincidentally with such increase 

 of the respiratory movements, however, there is diminution of the force 

 and tension of the pulse, as shown by the sphygmograph, which may to 

 some extent explain the fall. It thus appears that the temperature of the 

 body is not raised by exercise to the extent that might be expected, its in- 

 crease beyond a certain point being provided for by more rapid breathing, 

 the quicker circulation of the blood through the skin, and consequently 

 quicker cooling by radiation, sweating, etc., so that, as Wunderlich observes, 

 the opposing conditions of the loss of force by mechanical work and by quicker 

 cooling, and on the other hand the overplus through augmented chemical 

 action, compensate each other in health, and the fatal difference of tempera- 

 ture during rest and dtiriiii/ lnhnr is extremely trifling. 



iv. The influence of ingestion of food upon the temperature of the body 

 was found, in Dr. Ogle's and in Dr. Jiirgensen's experiments, to cause a 

 slight elevation of the temperature both of the mouth and of the rectum, 

 unless wine were consumed, when a decline occurred. Dr. Jiirgeuseu ob- 

 served no change beyond a slight depression of the mean diurnal temperature 

 after fasting for 26 hours; but when the abstinence was prolonged to a period 

 of 62 hours, the mean diurnal temperature rose and the usual period of de- 



1 Centralblatt, 1869, p. 781. 



2 Journal of Anatomy and Physiology, 1873, vol. vii, p. 117. 

 1 Pflii-cr's Archiv, Bd. iv, 1871, p. 283. 



* Brown-Sequard, Archives de Physiologic, t. i, 1868, p. 479. 



