CHEMICAL CHANGE AND HEAT PRODUCTION. 835 
following table of isodynamic foodstuffs is taken from Danilewsky's 
work : — 
Fat. 
Starch. 
G rape- 
Sugar. 
Cane- 
Sugar. 
Cellulose, i Peptone. 
Extract of 
Meat. 
100 grins. 
casein = 
100 grms. 
fat 
100 gnus. 
starch = 
61 
100 
46 
133 
220 
100 
151 
250 
114 
142 
236 
107 
133 121 
221 201 
100 92 
135 
224 
102 
The above data are for physical values. It is necessary, therefore, 
to determine how far the different foodstuffs undergo combustion in 
the living body, and what values they have as producers of heat during 
that combustion. 
Eubner has shown that some of the products of the combustion of 
proteid escape in the faeces as well as in the urine ; the heat value of 
these substances must be determined and deducted from the heat of 
combustion of proteid. The reduced or physiological heat value of 
1 grm. of dry proteid is therefore only about 4000 calories. The fats 
and carbohydrates appear to undergo complete oxidation in the body. 
An important series of experiments on the sources of animal heat 
has been performed by Paibner. 1 The experiments were carried on for 
several days in succession upon a dog weighing 12 kilos. The animal 
was given a known amount of meat once a day ; the urine and faces 
were collected and their heat of combustion determined, and the heat 
given off by the animal was measured by a calorimeter. At the same 
time the discharge of carbon dioxide and water from the dog were deter- 
mined, also the total nitrogen lost in the urine and faeces, and the loss 
or gain in weight of the animal. No external work was done by the 
dog, for it remained quiet in the calorimeter, and therefore no energy 
was lost in the form of work. 
The following i 
= an example of the 
results obtained : 
— 
Date. 
Condition. 
Total Dis- 
charge of 
Nitrogen. 
Carbon 
from 
Fat. 
Heat 
Calcu- 
lated 
from 
Proteid. 
Heat 
Calcu- 
lated 
from 
Fat. 
Total Heat 
in Twenty- 
four Hours. 
16th October 1889 
Fasting 
3-06 16-38 
77-0 
201-5 
278-5 kilo-cal. 
This result, 278'5 kilo-calories, compares well with the heat, 276-8 kilo- 
calories, given off by the animal in the calorimeter. 
Heat 
Date. , Condition. given to 
Calorimeter. 
Heat 
Lost in 
Ventilation. 
Heat Lest in 
Evaporation 
of Water. 
Total Heat 
in Twenty- 
four Hours. 
16th October 1S89 Fasting 213*2 
17-6 
45-9 
276-8 
kilo-cal. 
1 ZUchr.f. Biol., Miinchen, 1893-94, Bel. xxx. S. 73. 
