ON INCREMENT OF ANIMAL HEAT. 
417 
animal which^ covered in the same way, does not lose water 
by the perspiratory process. And again an animal, like 
man, who has a surfaee very lightly covered by nature, and 
at the same time a most elaborate cutaneous excretory sur¬ 
face, will have, mteris parihus, a lower temperature than both 
other classes. As showing this fact, let me write down a 
table which includes direct observations of my own, and 
which gives these observations corrected by those of Dr. 
John Davy, Pallas, Despretz, and Metcalfe. 
Temperature of Animals compared with Temperature of Man. 
Degrees, Fahr. 
Mean temperature of Man .... 
98 
55 55 
Sheep .... 
104 
5J 55 
Goat .... 
104 
55 55 
Ox .... 
101 
55 55 
Horse .... 
100 
55 55 
Cat .... 
102 
55 55 
Dog . 
102 
55 55 
Rabbit .... 
103 
55 5 5 
Guinea Pig 
102 
55 55 
Pigeon .... 
108 
55 55 
Common Powl . 
108 
55 55 
Duck .... 
108 
In recording these figures I have placed before 
you mean 
results. In the case 
of pigeons the mean is derived from 
ninety-four observations, in the human subject 
from one 
hundred observations. 
In all there have been fc 
lund indi- 
vidual differences, due to external temperature and other dis¬ 
turbing influences; but I believe the general deduction is 
accurate, and that the table is reliable. 
On looking over this table we might, a priori., suspect that 
those animals which have the highest natural temperature 
will most readily suffer from increment of heat on being sur¬ 
rounded with air heated beyond their own natural tempera¬ 
ture. This is the fact; and upon it we may try to determine 
two distinct points—first the temperature of the external air 
which is fatal from excess of heat, and secondly the incre¬ 
ment of temperature of the animal body which is fatal. 
In respect to the first of these determinations, I may state 
at once that, other things being equal, the power of an animal 
to live in a raised temperature is proportionate to its power to 
convey away heat by evaporation of water. Of all animals 
man, perhaps, possesses this power in the most marked 
degree. His skin and lungs are so actively called into play 
in heated air that he can survive in a temperature which 
