2A STORRS AGRICULTURAL EKXPERIMENT STATION. 
The energy of the income is the potential energy of the 
compounds of the food and drink. The energy of the outgo is 
of two kinds; the potential energy of the incompletely oxidized 
materials excreted, especially by the intestines and kidneys, 
and the kinetic energy given off from the body in the forms of 
heat and external muscular work. This leaves out of account 
other possible forms of energy which may be given off from _ 
the body. If there be such we have at present no exact 
knowledge as to their nature or how they may be detected 
and measured. It is conceivable, for instance, that mental 
activity may involve the transformation of potential energy 
into some hitherto unknown form of kinetic energy and that 
future experimenting with refinement of apparatus and meth- 
ods may indicate the existence of such metabolism of energy 
and explain its character and amount. But for the present we 
must be content to deal with the kinds of energy we are famil- 
lar with, and our first task is to measure these as accurately as 
may be. . 
The apparatus here described is intended and has thus far 
been used for experiments with men. There were several 
reasons for beginning with men rather than with domestic 
animals. The study of human nutrition is very important. 
In the earlier development of the work, when many difficulties 
were to be overcome, it was very desirable to have an intelli- 
gent person inside the apparatus rather than an animal whose 
movements could not be controlled. Indeed the most advan- 
tageous way to develop methods and apparatus for experiments 
with animals was through such preliminary experience with 
men. The results of the experience thus far gained are now 
being utilized in planning for apparatus to be used with small 
animals, as sheep and dogs. If this effort shall prove success- 
ful, as we have every reason to hope it may, the next step 
will be to devise apparatus and methods for experiments with 
larger animals, as horses, oxen and cows. 
It is to be remembered also that the fundamental laws of | 
nutrition are the same for domestic animals as for man and 
that better knowledge of these laws is pressingly needed as 
the foundation for proper understanding of the practical prob- 
lems which the farmer has to do with in the feeding of his 
stock. A great deal of the experimenting wh.ch is now being 




