248 
The Aj^plicatiom of Physiology 
in the present state of our knowledge, we cannot deny that a 
separation might take place by a simple alteration of the chemical 
nature of the components of the organism, without a change in 
composition : thus the alkalis liberated by the destruction of a 
tissue might possibly convert the albumen in the blood into 
casein, and thus the waste of the tissue would indirectly increase 
the amount of casein in the milk. The cases already cited might 
be explained on this supposition.* We have the more insisted 
upon this point, because by it may be explained several apparently 
anomalous circumstances in dairy-farming. 
The second principle connected with milk which we ought to 
consider is the production of its butter. We have already stated 
our experiments {Memoirs of the Chemical Socieii/, vol. i.) against 
the theory of Dumas, that the butter contained in the milk of a 
cow is solely derived from the fat in its food : this doubtless has 
a very considerable influence ; but we conceive that the formation 
of fat from starch, as pointed out by Liebig, is too well supported 
by agricultural experience to be denied. In the opinion of the 
latter chemist, fat, and consequently butter, is produced by a 
separation of oxygen from the elements of starch. The butter, 
when once formed, is very easily consumed by the oxygen of the 
air. 
Sugar-of-milk, or lactine as it is sometimes called, closely 
resembles starch in its chemical characters, and differs from it in 
composition only by containing more of the elements of water. 
According to Liebig {Animal Chemistry, p. 73), starch may be 
considered as composed of 12 atoms of carbon with 10 atoms of 
water, while sugar-of-milk may be viewed as starch, with 2 atoms 
of water in addition. Hence, in a chemical point of view, there 
is no difficulty in accounting for its formation. 
We are now prepared to consider the practice of dairying. 
In woman we find that anything Avhich tends to annoy her, to 
irritate her feelings, or produce an exhibition of anger, occasions 
at the same time a partial destruction of the valuable constituents 
of her milk. We have it in our power to observe these effects in 
woman with more accuracy than in the lower animals, though 
doubtless similar feelings will produce in both the same change in 
the composition of the milk. The milk of a woman who has 
experienced a violent and sudden fit of anger is found to be quite 
* It may be objected to this view, that, were the explanation now given 
correct, the milk obtained after calving should contain a large quantity of 
alkaline salts, while in reality the analysis of Boussingault gives an un- 
usually small proportion. But we have shown in another paper that the 
method employed l)y Boussingault lor estimating the ashes of milk is 
inaccurate ; and that the ashes in milk are always much higher than ex- 
hibited in his analyses. 
