8o6 
ANIMAL HEAT. 
Age. 
In the Stables. 
Age. 
In the Fields. 
4-6 years 
6-8 ,, 
8-18 „ 
38°-05 
37°-92 
37°-85 
4-6 years 
6-12 ,, 
12-18 ,, 
37 =, 40 
37 0, 24-37°-49 
37°-48 
The influence of muscular work.— During muscular work there is 
an increased production of heat, and were it not for the compensation 
brought about by the increased loss of heat the temperature of the body 
would rise considerably. The effect,~therefore, of muscular work upon the 
mean temperature varies according to the perfection of the compensation. 
Jiirgensen * found that the work involved in sawing wood for six hours 
raised the temperature of a healthy man l c- 2 above the normal, but 
as soon as the work was finished the temperature fell rapidly. Davy 2 
made numerous observations upon the effect of active exercise on his 
own temperature. The highest readings of the thermometer under the 
tongue were 37 0- 5 (99°'5) and 37°"8 (100°); some previous observations 
upon the temperature of men after walking two or three hours showed 
a rise of "8° in the temperature of the urine, but no change in that 
taken in the mouth; after a rest the temperature rapidly fell to the 
normal. Alpine climbing, even on cold days, was found by Clifford 
Allbutt 3 to raise the temperature of the mouth about half a degree ; 
the same form of exercise was taken by Liebermeister and Hoffmann, 4 
who observed the temperature in the axilla during both the ascent and 
descent ; the chief results were as follows : — 
Liebermeister's temperature, 36 c- 82 before ascent and 37°'85 maximum during ascent. 
Hoffmann's ,, 36° "50 ,, ,, ,, 37° "95 
Liebermeister's „ 36 o- 60 ,, descent ,, 37°"60 ., ,, descent. 
Hoffmann's ,, 36 '40 ,, ., ,, 37° - 25 ,, ,, „ 
Eesults directly opposed to the above have been obtained by Lortet, 5 
whose observations were made on level ground and during two ascents of 
Mont Blanc (4810 metres high) in August 18G9. On level ground Lortet 
found that, when he was at rest, the temperature of his mouth was 36° *4, 
but 36° - 2 during bodily exercise. During the ascents of Mont Blanc the 
temperature fell progressively and even reached as low a point as 31°*8, but 
after a few minutes' rest it rapidly reached the normal. Lortet explained 
these results by saying that during work the chemical forces which would 
have sufficed in the rarefied atmosphere to maintain the normal temperature 
of the body, were partly resolved in motion, and therefore the temperature 
fell. These results have been criticised by Clifford Allbutt and Liebermeister, 
and there can be little doubt but that the low temperatures observed were 
due to the cooling of the thermometer in the mouth by the laboured breathing 
of the cold air, which was sometimes several degrees below zero. This criticism 6 
1 " Die Kbrperwarme des gesunden Mensehen," Leipzig, 1873, S. 43-46. 
2 Phil. Trans., London, 1844, pt. 1, p. 62 ; 1S45, pt. 2, p. 322 ; 1850, p. 440. 
3 Journ. Anat. and Physiol., London, 1872, vol. vii. p. 106. 
4 Liebermeister, "Handbuch der Path. u. Therap. des Fiebers," 1875, S. 84. 
5 Compt. rend. Acad. d. se., Paris, 1869 p. 709. 
6 These sources of error have been shown to exist, for Arkle (experiments made at the 
request of the writer, and the results of which will be published later), during mountain 
climbing iu the summer of 1897, found a constant rise of two or three degrees in the 
rectal temperature, but the mouth gave a low temperature. In fact, it was impossible to 
obtain accurate results by placing the thermometer in the mouth. 
