Bauhaus-Universität Weimar

Titel:
The Cyclopaedia of Anatomy and Physiology, vol. 2: Dia-Ins
Person:
Todd, Robert Bentley
PURL:
https://digitalesammlungen.uni-weimar.de/viewer/image/lit25760/662/
654 ANIMAL HEAT. 
ture of the different classes, the results of which 
have been already stated. The comparison 
might be carried out in regard to Insects and 
the Mollusca, which present some appreciable 
differences. If attention were confined solely 
to the structure of the greater number of the 
organs of nutrition, which are much more 
largely developed in Molluscs, it might be 
inferred that they had a higher calorific power 
than Insects; but when we take into the account, 
1st, the final result of the nutritive functions, 
the quality of the tissues, which in the Mollusc 
are much more loaded with watery fluid, by 
which they acquire a greater degree of softness 
and flaccidity, (whence the class has its name,) 
whilst in the Insect they are, on the contrary, 
as remarkably dry and firm ;—2d, when the 
most general mode of respiration is compared 
in the two divisions, it being in the Insect 
aerial, in the Mollusc aquatic ; 3d and lastly, 
when we glance on the one hand and on the 
other at the state of the nervous system, and 
observe how much less perfectly this is developed 
in most of the Molluscs than in the Insect, it is 
impossible not to perceive that according to the 
principles influencing the production of heat, 
the Mollusca must be inferior in this respect 
to Insects. This is indeed the result of obser¬ 
vations of all kinds, however imperfect or 
limited these may have been, as we have seen 
above. 
It is impossible to carry the comparison 
further; the phenomena connected with heat 
in the lower grades of the auimal creation 
become inappreciable ; and this even in virtue 
of the same principle that has been an¬ 
nounced ; for the tissues are found to become 
more and more watery as we descend in the 
scale, till at length the solid constituent is 
almost inappreciable. Of course the circulating 
fluid must be watery in a still greater ratio ; it 
contains but few globules; and then the ner¬ 
vous system falls off in a still greater propor¬ 
tion ; it becomes more and more imperfect, till 
at length no trace of it is to be discovered. 
We thus arrive at the last links of the chain, 
after having run over the whole animal king¬ 
dom, and we have found one uniform principle 
of correspondence between organic modification 
and calorific power. It were difficult to imagine 
any more satisfactory proof of a principle than 
has been afforded ; indeed as this has on no 
one occasion been found belied, we are fully 
authorized to regard it as established. 
We have as yet examined but two points in 
reference to animal heat; 1st, the temperature 
of man and of the different classes of animals; 
2d, the general relations of organization with 
the production of heat. In mentioning the 
temperature in any case, we have spoken 
of it as determinate ; and farther, to have data 
that should be always comparable, the tempe¬ 
ratures have been taken regularly in the same 
places,—viz. the mouth in man, and the other 
extremity of the intestinal canal in animals. 
We have still to ascertain whether the tempera¬ 
ture varies or is identical in different parts of 
the body. 
Temperature of different parts of the body. 
—There is no need of the thermometer to tell 
us that all parts of the body do not at all times 
preserve the same temperature. We are 
often certain that the extremities are colder 
than the trunk for example; and a law of 
decrease of temperature in the ratio of the dis¬ 
tance of parts from the heart had even been 
deduced from this observation. But when 
exact measurements came to be taken, this law 
was soon found to be at fault, as will be seen 
by-and-by in the course of these observations. 
Dr. Davy, in taking the temperature of the 
different parts of the body of a lamb, found 
that of the right ventricle of the heart 40°, 5 
(105° F.), that of the left ventricle 41°, 1 (106° 
F.). The left ventricle was therefore higher in 
temperature than the right to the extent of a 
degree of the scale of Fahrenheit’s thermometer. 
The temperature of the rectum corresponded 
with that of the right ventricle. 
In my inquiries along with M. Gentil 
into the relations in point of temperature of 
certain external parts, we found in a strong 
man, perfectly at rest in mind and body, 
in the month of July, the external air being at 
21°, 25 c. (71° F.), the temperature of the 
mouth 38°, 75 (102° F.) ; that of the rectum 
corresponded. The hands presented the next 
highest degree, marking nearly 37°, 5 (99°, 5 F.). 
What is remarkable is that the axillae and 
groins, which corresponded with one another, 
were very sensibly lower in temperature than 
the hands ; they did not raise the thermometer 
higher than 36°, 9G c. (99° F.). The cheeks 
marked 35°, 93 (96°, 5 F.), the temperature 
being ascertained by enveloping the bulb 
of the thermometer in the skin of these 
parts. The feet were a little lower, 35° 62 
(about 96° F.) ; their temperature being deter¬ 
mined by placing the thermometer between the 
two, so that the bulb was surrounded on every 
side. The temperature of the feet was, there¬ 
fore, notably lower than that of the hands, 
differing to the extent of 1°, 88 of the centigrade 
scale (above 3° of Fahrenheit’s thermometer). 
Placed on the skin between the thorax and 
abdomen the thermometer was at its minimum, 
not rising higher there than 35° (95° F.) ; but 
here a part of the bulb being in contact with 
the air, there must have been considerable 
cooling. 
As the question here is not of absolute but 
merely of relative temperatures, we can make 
great use of the results come to by the different 
writers quoted. We shall present a summary 
of these under the following head. 
Relations between the temperature of inter¬ 
nal parts.—1st. The warmest part of the body, 
according to John Hunter, is in the abdomen 
close to the diaphragm. 2d. The next part in 
point of temperature is the left ventricle of the 
heart. 3d. The right ventricle of the heart is 
the next in succession. The rectum and the 
mouth shut are of the same temperature. The 
greatest difference consequently between the 
temperature of these internal parts does not 
amount to more than 1° centigrade, or at the 
utmost 2° Fahrenheit. 
Supposing the relations in temperature of the
        

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