246 
The Applications of Physiology 
permitted, the urine of the animal is richer in nitrogen than that 
voided in the stall ; for the nitrogenous matter of the tissues ex- 
pended in the production of force is separated from the system in 
the form of urine. In the stall-fed animal there is comparatively 
little waste of matter, and hence the value of the urine, in its 
ammoniacal ingredients, is considerably diminished. As less food 
suffices for the sustenance of the animal in the stall, this, together 
with the diminished waste of its tissues, decreases the amount of 
manure, and renders it poorer in inorganic ingredients than that 
furni.shed by grazing animals. The opposite opinion is generally 
entertained. This arises from the circumstance that the manure 
from stall-fed animals is more efficacious, both from its better 
preservation and more profitable distribution over the land. Still 
this does not invalidate the conclusion, that the manure of an 
animal fed in the field is of more value in a chemical point of 
view than that of one fed in the stall upon the same food. 
Yet it would be very absurd to use this as an objection to the 
introduction of stall-feeding, as, in such a case, the objector must 
be prepared to assert that the manure obtained from an animal is 
of more value than its flesh ; for the increased value of the dung 
of a grazing animal arises from a waste of its muscular apparatus. 
When cattle are fed on artificial food, the composition of the 
manure depends upon the quantity of inorganic ingredients con- 
tained in the food consumed. Thus 100 lbs. of mangold-wurzel 
contain only 1 lb. of earthy matter, while the same quantity of 
linseed-cake contains 7 lbs. of the same ingredients. But as only 
a certain portion of the latter is necessary for the formation of the 
bones, the remainder is separated by, and enriches, the excre- 
ments. Hence it is that certain kinds of food produce more 
valuable manure than others. 
III. We have now to consider one of the most important 
branches of feeding cattle, viz. for dairy purposes. Attention 
to scientific principles, in this department of feeding, is likely to 
lead to the most beneficial results. 
Milk is one of the most important secretions of the body. It 
has already been stated that it consists of casein (cheese), butter, 
sugar-of-milk, and various earthy and alkaline salts. Potash is 
perfectly indispensable to its formation : indeed, this alkali seems 
to be the means by which the albumen in the body is rendered 
soluble, and consequently converted into casein. We know little 
or nothing of the nature of secretion : we only know that certain 
glands have the power of appropriating particular parts of the 
organism or of food, in order to produce fluids, which are either 
separated from the system, or perform some new functions in it. 
In the secretions the chemical forces play an important part, al- 
though the peculiar nature of their action is but imperfectly 
