618 
Journal of Agricultural Research 
Vol. XXIX, No. 12 
from knowing all the factors which 
affect these relationships, and the 
physiological conclusions to be drawn 
from such experiments as those which 
have just been presented must, there¬ 
fore, be more or less tentative for a 
long time to come. But the manner 
in which diet affects the composition 
by additional work more extensive 
than can be carried out by a single 
investigator. In the meantime it is 
worth while to set forth some of the 
conclusions which appear to be reason¬ 
ably justified, though perhaps not 
fully established, by the work done 
so far. 
/JO 
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Fig. 4.— Experiments I, II, III, V, and VI. Change of milk yield when amount of protein or energy, 
or both, were increased in ration after a period of reduced feeding. Yields at end of previous period taken 
as 100 per cent 
of the blood and in which this again 
affects the various bodily activities 
are matters of such fundamental 
physiological importance that it will 
be profitable to determine and record 
the facts in this field even though 
their full significance cannot be re¬ 
alized until they are supplemented 
In order to interpret the results 
which are to be considered in this 
section, it is necessary to bear in 
mind that the lactose, fat, and pro¬ 
teins of milk are made in the mammary 
gland from glucose, phosphatide, and 
amino acids, respectively, that are 
taken from the plasma of the blood. 
