such narrow limits as to be quite
insignificant.]

[Footnote 7: Doubt has recently been thrown on the truth of this belief
by Frankland, Fick, and Wislicenus.]

[Footnote 8: The results of Savory's experiments on rats appear to prove
that animals can live on food destitute of fat, sugar, starch, or any
other fat-forming substance. I think, however, that animals could hardly
thrive on purely nitrogenous food. The conclusions which certain late
writers, who object to Liebig's theory of animal heat, have deduced from
Savory's investigations, appear to me to be quite unfounded.]

[Footnote 9: So termed because it is the basis of the common oils; the
fluid portion of fat is composed of oleine.]

[Footnote 10: The term _dry_ is applied to the _solid_ constituents of
the food. Thus, a pig fed with 100 lbs. of potatoes would be said to
have been supplied with 25 lbs. of dry potatoes, because water forms
75 per cent. of the weight of those tubers.]

[Footnote 11: The amounts of "mineral matter" are too high, owing to the
adventitious matters (dirt) retained by the wool.]

[Footnote 12: This pig was completely analysed by Lawes and Gilbert.]

[Footnote 13: The results of recent and accurately conducted
investigations prove that men engaged in occupations requiring the
highest exercise of the intellectual faculties, require more nutritious
food, and even a greater quantity of nutriment, than the hardest worked
laborers, such as paviours, and navvies. I have been assured by an
extensive manufacturer, that on promoting his workmen to situations of
_greater_ responsibility but _less_ physically laborious than those
previously filled by them, he found that they required more food and
that, too, of a better quality. This change in their appetite was
not the result of increased wages, which in most cases remained the
same--the decrease in the amount of labour exacted being considered in
most cases a sufficient equivalent for the increased responsibility
thrown upon them.]

[Footnote 14: As ammonia, urea, uric acid, or hippuric acid; all of which
are nearly or perfectly mineralised substances.]

[Footnote 15: The excrements of animals are capable of evolving, by
combustion, enormous amounts of heat.]

PART II.

ON THE BREEDING AND BREEDS OF STOCK.

SECTION I.

THE BREEDING OF STOCK.

_Cross Breeding._--For many years past feeders have zealously occupied
themselves in the improvement of their stock, and the resu