Several of our prominent dairy writers have been lately
discussing the more complicated questions of their department
in a very energetic and decided, if not in a scrupulously exact
manner. Now, if these questions are worth the time and space
necessary for their presentation at length, they are certainly
of sufficient importance to receive candid and perfectly
truthful treatment; and, though these writers may not have
intended to give wrong impressions, their teachings can hardly
be considered, in several respects, as representing the present
condition of knowledge on these points.
MAGNE’S THEORY OF THE ESCUTCHEON.—In Mr. Eastburn Reeder’s
essay on the escutcheon—which is a valuable paper, though
marred in the above respects—there is an attempt at scientific
argument in order to ridicule the accepted value of the
milk-mirror; and the assumed facts on which this argument is
based, are presented in such a positive manner that they will
probably be accepted, without further investigation, by the
majority of readers unless contested at once. The writer has
hesitated to do this in the hope that it would be done by some
one else; but the truth is of too much consequence to allow the
matter to pass entirely without notice.
The first point to which I will call attention is the attempt
to dispute Magne’s opinion that the hair turns in the direction
in which the arteries ramify, and that the reversed hair on
the udder and adjacent parts indicates the termination of the
arteries which supply the udder with blood. When these arteries
are large, he holds, they extend through the udder upward and
onward, ramifying on the skin beyond the udder, and giving the
hair the peculiar appearance which distinguishes it from the
rest of the surface. If these arteries are very small, they are
not likely to extend much beyond the udder, and, hence, form a
small escutcheon; consequently, a small escutcheon indicates a
feeble supply of blood, and little material to make milk of.
Now how is this combatted? The first argument is that “when Mr.
Hardin showed this paragraph to one of the most learned medical
professors at Louisville, Kentucky, he at once wanted to know
who this Magne was, and declared his name unknown in the annals
of medical science.” What are we to think of such a statement
as that? Magne—member of the French Academy of Medicine,
formerly director of the Alfort Veterinary School and professor
of Lyons—unknown in the annals of medicine!
We are then asked if the arteries are not the same in all
cows, and are told that we might as well expect more bones or
muscles as more arteries. If Mr. Reeder will turn to Chauveau’s
Anatomy—one of the best authorities in the world—he will find,
in general remarks on arteries, the following statement, which
I translate, not having the English edition: “Arteries very
often present variations in their deposition, which the surgeon
should keep in mind. These variations ordinarily concern the
number, the point of origin, and the volume of the vessels.”
And if he will go through the list of arteries, he will find
examples given of each of these variations.
Again, he asks, “how is it that the ramification of the
arterial circulation _causes_ the hair to grow in one direction
on one part of the cow’s body, and in the opposite on other
parts?” Not a very difficult question, if we admit that
arteries have such an effect, for they certainly do not all
ramify in the same direction.
In a revised edition of the essay, subsequently published,
some important points were added. Here we are told that
“the arteries supplying the udder with blood are called the
_mammary_ arteries, and their ramification _does not extend
beyond the outer surface of the udder_. Further down the
_aorta_, or main artery, another pair of arteries branches off,
called the _femoral_ arteries. These supply the muscles of the
thigh, or what we know as the _rounds of beef_, with blood,
and ramify upon the portion of the escutcheon lying between
them. Still further down, another pair of arteries, called the
_gluteal_ arteries, leave the _aorta_, and are distributed
through the pelvic region, and ramify upon the extreme upper
portion of the escutcheon. Here we have at least three distinct
systems of arteries ramifying upon the escutcheon, and _two_ of
them most certainly have no connection with the milk secretion
whatever.”
Without attempting to point out _all_ the errors of this
description, we will once more refer to Chauveau to settle the
more important points. The reader will find in that work that
the _femoral_ arteries have a branch called the _pre-pubic_,
which in turn has a branch called the _external pudic_, from
which the _mammary_ artery branches. It will also be found
that the mammary artery “sends several divisions to the
tissue of the udder, and is prolonged between the thighs by a
perineal branch, which terminates in the inferior commissure
of the vulva, after having furnished glandular and _cutaneous_
divisions.” Turning to the description of the gluteal arteries,
we find that they ramify in the gluteal muscles, which are at
a considerable distance from the perineum, and that nothing is
said of their going to the last named part.
Here, then, is complete and positive refutation of these
arguments—not by mere statements of my own, but by the words of
a standard work, of world-wide reputation, on the anatomy of
these animals. Magne’s _facts_ are correct, then, whether his
inferences are or not. _The same artery that supplies the udder
with blood supplies the skin on which the escutcheon is formed;
and, more than this, the artery ramifies in the direction
in which the hair of the escutcheon grows._ Is there any
connection between the two for all that? Who knows? A point or
two to show that such a connection is not beyond the possible
may still be in place.
Erasmus Wilson, who has made a specialty of the skin and its
diseases, shows that the direction of the hairs on the anterior
surface of the human body is, commencing at a point near the
arm-pit, downwards and slightly inwards towards the umbilicus,
and that below this point the direction is upwards and inwards;
so that the umbilicus “is the center of convergence of four
streams,” as he expresses it.
Now this disposition, complicated though it is, certainly
resembles that of the arteries—the branches from the _axillary_
artery passing downwards and inwards, while the _epigastric_
arteries branch from the _femorals_ near the groin, and have
a direction upwards and inwards. On the neck, the direction
of the hair is upwards and backwards; in front of the ear, it
is downwards and forwards; behind the ear, it is backwards—in
each case following the arterial ramifications. In addition,
Tisserant and others in France, who stand high as authorities,
admit that the escutcheon continues to increase in relative
surface till the second or third milking—that is, till the
development of the udder, and, consequently, of the vessels
supplying it have reached their highest point.
In some cases, it must be confessed, the correspondence in
question apparently does not exist, but rather the opposite;
and as the mammary artery has substantially the same
distribution with horses as with cattle, we cannot see why the
former should not be as plainly marked as the latter, if the
direction of the hair depends on the direction of the arteries.
But, it may be asked, in what possible manner could the one
condition influence the other? It must be remembered that
physiology is still a growing science, and that there are
many things yet to learn, so that it is still pardonable to
confess ignorance. We know, however, that the cavity in the
skin surrounding the hair (hair follicle) is set in an oblique
direction, as well as the hair that emerges from it; the
papilla at the bottom of this cavity must also be inclined,
and it is this that, in all probability, decides the direction
of the hair, as the growth of this takes place by additions
of cells from the surface of the papilla. Now, each papilla,
or elevation, has a vascular loop, or, as some say, a minute
artery and vein, and one can easily imagine how the direction
of this minute artery might influence the direction of the
papillary summit, and, consequently, of the hair that grows
from it.
I do not say that this is the proper explanation, but I suggest
it as one way in which the correspondence might be accounted
for. I do say, however, that the evidence brought to bear on
this point by Mr. Reeder can have no influence in deciding the
question, for the reason I have given.
Dr. Henry Stewart, the noted scientific and practical farmer
and writer, said lately; “I have for some time past been
studying the nature of the escutcheon physiogically and
anatomically.” And he has “recently discovered a still more
satisfactory connection between the milking capacity of a cow
and the development of the escutcheon.”
“The milk-vein is an important mark of the deep-milking cow.
But it is not the veins, but the arteries, which supply blood
to the system, either for the production of tissue or the
secretion of the milk. And yet the veins are important because
they bear a direct relation to the arteries, being the return
channels for the blood after it has fulfilled its functions;
and so the larger supply of blood conveyed by the arteries
requiring a vein of large capacity to return it, this vein is
an ultimate indication of the vigor of the circulation of the
lacteal organs. The main artery which supplies these organs
is the subcutaneous abdominal [what Mr. S. says is commonly
called the milk-vein.] This important artery supplies a large
part of the posterior portion of the system, furnishing blood
to the genital organs and the skin covering these and the
adjacent parts. The subcutaneous abdominal artery is one of the
two branches of the external pudic artery in the female, the
other being the mammary artery. This last is very voluminous
and distributes several main branches to the mammary glands
and tissue, and also by a prolongation between the thighs,
supplies the inferior commissure of the vulva and gives off
many smaller branches, which spread into a network among the
glandular tissue and the cutaneous structure. Here is the close
connection, then, between the skin of the posterior part of the
cow, from the lower point of the vulva down between the thighs
and around the udder, and the udder itself. The same artery
supplies all this portion of the skin, furnishes the subaceous
glands and the hair follicles, and the whole cutaneous
structure, and the hair also with blood, and also provides
for the demands of the milk-secreting organs. A vigorous
circulation through a voluminous arterial system ... gives a
relatively vigorous milk secretion, and, as well, a growth of
hair, which curls and forms the well-known peculiar structure
of the escutcheon.”