h have been passed upon Guenon's method of
judging of cows, the best breeders and judges of stock concur in the
opinion, as the result of their observations, that cows with the most
perfectly developed milk-mirrors are, with rare exception, the best
milkers of their breed; and that cows with small and slightly developed
milk-mirrors are, in the majority of cases, bad milkers. There are,
undoubtedly, cows with very small mirrors, which are, nevertheless,
very fair in the yield of milk; and among those with middling quality of
mirrors, instances of rather more than ordinary milkers often occur,
while at the same time it is true that cases now and then are found
where the very best marked and developed mirrors are found on very poor
milkers. These apparent exceptions, however, are to be explained, in the
large majority of cases, by causes outside of those which affect the
appearance of the milk-mirror. It is, of course, impossible to estimate
with mathematical accuracy either the quantity, quality, or duration of
the milk, since it is affected by so many chance circumstances, which
cannot always be known or estimated by even the most skillful judges;
such, for example, as the food, the treatment, the temperament,
accidental diseases, inflammation of the udder, premature calving, the
climate and season, the manner in which she has been milked, and a
thousand other things which interrupt or influence the flow of milk,
without materially changing the size or shape of the milk-mirror. It
has, indeed, been very justly observed that we often see cows equally
well formed, with precisely the same milk-mirror, and kept in the same
circumstances, yet giving neither equal quantities nor similar qualities
of milk. Nor could it be otherwise; since the action of the organs
depends, not merely on their size and form, but, to a great extent, on
the general condition of each individual.

[Illustration: MILK-MIRROR [B.]]

[Illustration: MILK-MIRROR [C.]]

The different forms of milk-mirrors are represented by the shaded parts
of cuts, lettered A, B, C, D; but it is necessary to premise that upon
the cows themselves they are always partly concealed by the thighs, the
udder, and the folds of the skin, which are not shown, and therefore
they are not always so uniform in nature as they appear in the cuts.

[Illustration: MILK-MIRROR [D.]]

Their size varies as the skin is more or less folded or stretched; while
the cuts represent the skin