PHYSIOLOGY. 
or burial places, or certain gases, as sul- 
pluirated and phosphorated hydrogen pro- 
duce it; there seems to be an action of 
some poisonous or deleterious substances on 
the nervous system through the medium of 
the lungs. Intoxication is quite diflFerent 
from asphyxia ; it induces a profound sleep 
or insensibility, in which the pulse still 
beats, and respiration goes on, although 
slowly. 
Tlie lungs are organs of secretion, and 
separate from the venous blood, circulating 
through them in the pulmonary artery, and 
loaded with serum, a very abundant watery 
vapour, called the breath, and shewing it- 
self in separate globules when condensed by 
a cold and smooth surface, as that of glass 
or metals. As the cessation of respiration 
is one of the most obvious and easily recog- 
nizable symptoms of death, the intimate 
connection between it and life has been 
noticed even by the vulgar, and hence 
life itself, and even the soul, have been sup- 
posed to reside in the breath. Thus ani- 
ma, in Latin, denotes the breath, the life, 
or the soul. The breath of life is a fami- 
liar phrase in our own language, and the 
“ animam efflavit” of the poet, which lite- 
rally means “ blew out his breath,” is em- 
ployed to signify “ died.” We cannot admit 
that this watery vapour is formed by the 
oxygen of the atmosphere uniting with the 
hydrogen of the venous blood, as this com- 
bination, performed out of thp body, is 
attended with phenomena of deflagration 
that do not occur in the present instance. 
The quantity of this secretion is said to 
equal that of the skin ; it should be distin- 
guished from the mucus secreted on the 
interior surface of the bronchiae and trachea, 
which is thrown off by strong expirations, 
and forms the matter of expectoration. 
Animal Heat. The power which living 
bodies possess of maintaining the same de- 
gree of heat under every change of sur- 
rounding temperature, is one bf their 
most surprising phenomena, and one which 
occupies a very prominent station in that 
complicated assemblage of circumstances 
denoted by the term life. The tem- 
perature of the blood, and of the interaal 
parts of the body in general, is stated 
at about 98° Fahrenheit. lu Mr. Hun- 
ter’s experiment, he found the heat under 
the tongue, and at the bulb* of the ure- 
thra, to be 97" ; in the rectum 98f ; in the 
rectum of an ox and rabbit 99^° ; of a hen 
103 ; in the heart, liver, and stomach of 
animals 100“ and 101“. ^ese tempera- 
tures, instead of varying like those of ina- 
nimate bodie.s, according to the surround- 
ing media, and consequently tending to a 
state of equilibrium, are maintained with 
very little deviation under very great varie- 
ties of atmospheric heat. Pallas sustained • 
a cold of 80“ below 0 in Siberia, and Gme- 
lin of 126“ in the same country. On the 
contrary, temperatures of 120“ and more, 
above 0 have been observed in Africa and 
America. Linings saw the thermometer at 
126“ in Carolina ; but when placed under 
the tongue, or in the axilla, it sunk to the 
point of animal heat. Much higher de- 
grees of artificial temperature have been 
supported by the human body. Girls in 
France staid in an oven where fruit and 
meal were baking, for ten minutes, without 
inconvenience, the thermometer at 265“. 
Dr. Fordyce and Sir Joseph Banks sup- 
ported nearly an equal degree of artificial 
heat in this country. 
From these facts it is obvious that, al- 
though in rare instances, the surrounding 
heat is greater than that of our own bodies, 
it is generally considerably less. Hence 
we must explain the povi ers by which our 
temperature is maintained so much above 
that of the medium in which we live. This 
explanation is now generally founded on the 
chemical changes which the blood under- 
goes in the lungs, and in its circulation 
through the body, which subject is con- 
sidered under the article Heat. There 
are many circumstances in favour of this 
explanation; as the increased heat pro- 
duced by the acceleration of the circula- 
tion from exercise. See. the coldness of a 
limb, when the nutrient artery is tied; 
the various degrees of temperature in dif- 
ferent animals corresponding with the per- 
fection of their pulmonary system, &c. 
There are also several facts which show 
that the living powers of the constitution, 
or part, greatly influence the evolution of 
heat, independently of the consumption of 
oxygen in respiration. The coldness of 
palsied limbs, the increased heat of parto 
in inflammation, and of the whole skin in 
febrile complaints, are sufficient to prove 
this. But it is most clearly demonstrated 
by an experiment of Dr. Currie’s. He 
placed a man in a cold bath of 40“, which 
at first diminished his temperature, but it 
soon regained the natural standard. Here 
there must have been a great evolution of 
heat to keep up the temperature under 
circumstances so strongly tending to de- 
press it; yet the consumption of oxygen 
was less than usual, for both the pulse and 
respiration became slower. Mr. Hunter 
