8o6 



ANIMAL HEAT. 



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 effeot^theref ore, of muscular work upon the 

 mean temperature varies according to the perfection of the compensation. 

 Jlirgensen l found that the work involved in sawing wood for six hours 

 raised the temperature of a healthy man 1*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 37'5 (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 '82 before ascent and 37 '85 maximum during ascent. 



Hoffmann's ,, 36 '50 ,, ,, 37 '95 ,, ,, ,, 



Liebermeister's ,, 36'60 ,, descent,, 37'60 ., ,, descent. 



Hoffmann's ,, 36'40 ,, ,, ,, 37'25 ,', ,, 



Results 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 1869. On level ground Lortet 

 found that, when he was at rest, the temperature of his mouth was 36 '4, 

 but 36 0< 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 



" Die Korperwarme des gesunden Menschen," Leipzig, 1873, S. 43-46. 



2 Phil. Trans., London, 1844, pt. 1, p. 62 ; 1845, 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. sc., 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 in 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. 



