224 
The Applications of Pliijsiologrj 
corn plants, or to agriculture generally. The object of agricul- 
ture is to produce an abnormal increase of some particular con- 
stituent of a plant, such as of gluten in the wheat. Tiiis we do 
by chemical ineans — by manure. The fattening of cattle is simi- 
lar. Our object is to produce an unnatural increase of some par- 
ticular parts of the body ; and to do this we must put the cattle in 
an unnatunal state. 
Fat is not an organ possessing shape ; it is not a substance pecu- 
liar to the animal economy. We find the fat of beef and mutton 
in cocoa-beans, of human fat in olive-oil, of butter in palm-oil, 
and of horse fat and train-oil in certain oily seeds (Liebig). In 
these the fat must arise, just as in animals, by the same chemical 
process of an imperfect transformation. 
The most favourable conditions to the developement of tallow 
are food destitute of nitrogen, warmth, and want of exercise. We 
shall return to this subject again, but now may remark that 
warmth is perfectly indispensable to the production of tallow in 
an animal. Tallow is so easily consumed by the oxygen of the 
air that it is employed to produce animal heat, if there be any 
deficiency in this. Martell {Trans. Linn. Soc, vol. xi, p. 411) 
mentions the case of a fat pig which was overwhelmed in a slip of 
earth, and lived for 160 days without food ; and was found to have 
diminished in weight during that time 120 lbs. Its fat had been 
consumed in supporting respiration, just as that of hibernating 
animals during winter. Motion also diminishes the tendency of 
an animal to fatten, by increasing the number of its respirations, 
and therefore by giving to the system an increased supply of 
oxygen gas, which consumes the tallow. Hence our practice of 
stall-feeding cattle. But, before entering into the discussion of 
practical points, let us fully understand the principles involved in 
fattening. 
First, then, let us Inquire what are the phenomena which attend 
the production of motion in any animal. Liebig asserts, and we 
quite agree with him, " that every motion, every manifestation of 
force, is the result of a transformation of the structure or of its 
substance ; that every conception, every mental affection, is fol- 
lowed by changes in the chemical nature of the secreted fluids; 
that every thought, every sensation, is accompanied by a change 
in the composition of the substance of the brain," 
I have already stated that there is a constant conflict in the 
body between the two antagonist powers. Vitality and Chemical 
Aflinity. In the state of health. Vitality retains the ascendancy, 
and subdues the Chemical powers ; but this subjection is the 
result of much effi^rt on the part of Vitality, for the strength of 
the rival forces is nearly equal. The moment, therefore, that 
Vitality leaves undefended a single point in the fortress of the 
