
104 STORRS AGRICULTURAL EXPERIMENT STATION. 
Two great laws govern the material world, the laws of the 
conservation of matter and of energy. In accordance with 
these laws matter and energy can be transformed, but they 
cannot be either created or destroyed by means known to man. 
Ever since the law of the conservation of energy was pro- 
pounded, men of science have believed that the living organ- 
ism must be subject to it, but the absolute demonstration has 
been lacking. ‘The research by which this must be proved, if 
proved at all, is laborious and costly. Some late experiments, 
however, have, it is safe to say, indicated that the law does 
hold in the living organism; that when the energy of the food 
is transformed in the body, the income and outgo are the same. 
The experiments are made by measuring the material which 
the body burns, determining how much heat it would yield if 
burned directly with oxygen outside the body, and then find- 
ing just how much energy is produced when it is burned in 
the body. | 
Investigations by Rubner* in Germany and by Laulaniet 
in France had brought results fully in accordance with the law 
of the conservation of energy, but their experiments were made 
with small animals—dogs, rabbits, etc., and were comparatively 
few in number; the experimental periods were rather short; 
the analyses of food, drink, and excreta were not catried out 
in great detail, and no experiments were made in which ex- 
ternal muscular work was involved. It was felt that the 
demonstration would be more nearly complete and on the 
whole much more satisfactory if the subjects of the experi- 
ments could be men, and preferably men who were familiar ~ 
with the methods of scientific research; if the experimental 
periods could cover several days each instead of being limited 
to a day or a few hours; if complete analyses could be made of 
the food, drink, and excretory products, the heats of combus- 
tion of the unoxidized materials being likewise directly deter- 
mined in each case; if the experiments could cover different 
conditions as regards food and fasting, work and rest; if ex- 
ternal muscular work could be performed and measured and 
finally if the experiments could be repeated with the same sub- 
ject and with different subjects. So extensive a program was 

* Ztschr. Biol. 30 (1894), p. 119 ef seq. 
+ Arch. Physiol. Paris (1898), p. 748. 
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