852 ANIMAL HEAT. 
result that it quickly boiled, owing to the absence of evaporation ; 
whereas the water in the other jar rose to 60°, but did not boil, evapora- 
tion taking place freely from the surface and thus cooling the water. 
Upon the loss of heat by evaporation Crawford, 1 in 1781, made some 
interesting experiments upon frogs ; he compared the rates of warming 
of a dead and a living frog by exposure to warm air and to warm water, 
and found that the temperature of the former rose more rapidly than 
that of the latter. 
In another experiment he found that, when the air was 25°, the skin of a 
living frog Avas 20°, the stomach 21° - 4; when the water was 16 0, 1, the skin of 
a living frog was 16°*2, the stomach 19°"2. It is to be noted that Avhen the 
frog was kept in water its nose was above the surface, so that it might breathe ; 
in this way heat might be lost by evaporation from the lungs. CraAvford, 
however, concluded from his experiments that the cooling Avas not solely due 
to evaporation, and that animals bad the power of " producing cold." 
In 1810, Delaroche" 2 published some instructive experiments, similar to 
those of Blagden, to sIioav the effect of evaporation. He placed an alcarraza 3 
full of Avater at 35°, and a rabbit Avhose temperature Avas 39° *7, in a stove 
heated to 15° ; the temperature of the rabbit gradually rose to 43°"8, Avhile 
that of the alcarraza fell to 31° - 4, and remained stationary. In the second 
experiment he placed a frog and tAVO pieces of moist sponge in a stove heated 
to 36 0, 5, and found at the end of an hour that the frog's temperature was 
stationary at 2S 0, 2, and that of the pieces of sponge at 27°*9 and 27° - 6. 
Delaroche contests the results of CraAvford's experiments on frogs, and main- 
tains that these animals quickly take the temperature of the Avater in which 
they are placed, and that in this respect there is no difference betAveen a dead 
and a living frog. 
According to the calculations of Vierordt and Ludwig, from 10 to 20 
per cent, of the total daily loss of heat in an adult man is due to 
evaporation from the skin and respiratory tract. Further details on the 
discharge of water from the skin and lungs are given in another part of 
this work. 4 The following values for the discharge of moisture from 
various parts of the human skin were observed by Waller : 5 — 
Palm of hand . 
24 
mgrms. 
per 
20 
sq. 
cm. 
(per 
10 
minutes)^ 
Sole of foot 
14 
)5 
}> 
Forehead 
12 
>) 
)> 
External 
Cheek . 
Axilla . 
Popliteal space 
6 
10 
10 
5> 
)» 
>> 
) tempera- 
ture, 20° 
Forearm . 
5 
>) 
>> 
Leg 
5 
J5 
>5 
I 
The influence of the size of the body upon the regulation of tem- 
perature.— The importance of the relation between the surface of the 
body and its mass, in respect to the loss and production of heat, was first 
pointed out by Bergmann. 6 The bigger an animal the greater the ratio of 
1 Crawford, Phil. Trans., London, 1781, vol. lxxi. p. 485. 
2 Delaroche, Journ. de phys., Paris, 1810, tome lxxi. pp. 294-296. 
3 A porous jar used for keeping water cool in hot climates. See also Edwards, "De 
l'influence des agens physiques sur la vie," p. 84. 
4 "Chemistry of Respiration," this Text-book, a t o1. i. p. 711. 
3 " Proc. Physiol. Soc," Journ. Physiol., Cambridge and London, 1894, vol. xv. For 
farther observations see Hale White, Crooniau Lectures, Lancet, London, 1897, June 19 
and 26, and Brit. Med. Journ., London, 1897, vol. i. p. 1654 et seq. 
6 "Gottinger Studien," 1847, Abth. 1, S. 595. 
