e , 
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ro * sd Sa 
a ae 
. Sr » 
= — a = 4 ¢ : : 
EXPERIMENTS ON METABOLISM OF ENERGY. cimat Ca? | 

a tas 

not form a part of the work of this Station, are soon to be 4 
reported in detail elsewhere. 
Each metabolism experiment, or series of experiments, was 
} immediately preceded by a digestion experiment of several days <s 
duration, in which the subject had the same diet as in the met- : 
abolism experiment, the purpose being to bring the body into 
approximate nitrogen and carbon equilibrium before the begin- 
ning of the metabolism experiment proper, and at the same 
time to secure a more nearly accurate measure of the digestibil- 
ity of the food. It is almost impossible to obtain exact nitro- 
gen equilibrium, since physiological factors, little understood 
and not easily controlled, cause more or less fluctuation in the 
elimination of nitrogen, even when the amount in the diet is 
uniform. These preliminary digestion experiments were gener- 
ally of four daysduration. Metabolism experiments Nos. 1-4, 
however, were preceded and followed by digestion periods of 
three days, while some later experiments were preceded by per- 
iods of usuaily four days, but sometimes more orless. In these 
-prelimininary digestion experiments the income and outgo 
of nitrogen were determined, so that the nitrogen metabolism 
— was measured and in this sense they are metabolism experi- 
; ments, although they are not here so designated, this term being 
= reserved for experiments in which carbon was also taken into 
ss account. There were altogether forty-four digestion and nitro- 
gen metabolism experiments which accompanied or made a part 
of the thirty-four experiments with the respiration calorimeter. 
They cover two hundred and one days. Only a small number: 
_---_—___ of the results of these digestion experiments, viz., those belong- 
B ing to metabolism experiments Nos. 1-4, have yet been pub- 
lished. 
The larger part of the seven years in which the work con- 
nected with the respiration calorimeter has been going on was 
devoted to the developing and perfecting of apparatus and ex- 
perimental methods; yet during the progress of the inquiry a 
mass of data has been accumulated and results bearing upon a 
variety of the questions enumerated on pages 97-99 have been 
obtained. 
While it is true that none of these topics can be discussed to 
the best advantage until the publication of further experiments 
or without due consideration of the results of research elsewhere, 
hie, hee ee io ae) ey ey Pa eee ~ patie ake Paha’ 
a ae ere ee eee vile St, 

