Part 24 (1/2)

MONSTROSITY IN THE CALF.

As a monstrous development in the calf may hinder calving, it is well to consider shortly the different directions in which these deviations from the natural form appear. Their origin and significance will be rendered clearer if we divide them according to the fault of development in individual cases. Monsters are such--

(1) From absence of parts--absence of head, limb, or other organ--arrested development.

(2) From some organ being unnaturally small, as a dwarfed head, limb, trunk, etc.--arrested development.

(3) From unnatural division of parts--cleft lips, palate, head, trunk, limbs, etc.--abnormal growth.

(4) From the absence of natural divisions--absence of mouth, nose, eye, a.n.u.s; the cloven foot of ox or pig becomes solid, like that of the horse, etc.--confluence of parts which are rightfully separate.

(5) From the fusion of parts--both eyes replaced by central one, both nostrils merged into one central opening, etc.--confluence of parts.

(6) From unnatural position or form of parts--curved nose, neck, back, limbs, etc.--lack of balance in the growth of muscles during development.

(7) From excessive growth of one or more organs--enormous size of head, double p.e.n.i.s, superfluous digits, etc.--redundancy of growth at given points.

(8) From imperfect differentiation of the s.e.xual organs--hermaphrodites (organs intermediate between male and female), male organs with certain feminine characters, female organs with certain well-marked male characters.

(9) From the doubling of parts or of the entire body--double monsters, doubled heads, doubled bodies, extra limbs, etc.--redundant development.

(Pl. XIX, figs. 1, 2, 3.)

_Causes._--The causes of monstrosities are varied. Some, like extra digits, lack of horns, etc., run in families, which produce them with absolute certainty when bred in the direct line, although they were originally acquired peculiarities which have merely been fixed by long habit in successive generations. The earliest horse had five toes, and even the most recent fossil horse had three toes, of which the two lateral ones are still represented in the modern animal by the two splint bones. Yet if our horse develops an extra toe it is p.r.o.nounced a monstrosity. A more genuine monstrosity is the solid-hoofed pig, in which two toes have been merged into one. Another of the same kind is the solid shank bone of the ox, which consists of two bones united into one, but which are still found apart in the early fetus. Though originally acquired peculiarities, they now breed as invariably as color or form.

Other monstrosities seem to have begun in too close breeding, by which the powers of symmetrical development are impaired, just as the procreative power weakens under continuous breeding from the closest blood relations. A monstrosity consisting in the absence of an organ often depends on a simple lack of development, the result of disease or injury, as a young bone is permanently shortened by being broken across the soft part between the shaft and the end, the only part where increase in length can take place.

As the result of the injury the soft, growing layer becomes prematurely hard and all increase in length at that end of the bone ceases. This will account for some cases of absence of eye, limb, or other organ.

Sometimes a monstrosity is owing to the inclosure of one ovum in another while the latter is still but a soft ma.s.s of cells and can easily close around the first. Here each ovum has an independent life; they develop simultaneously, only the outer one having direct connection with the womb and being furnished with abundant nourishment advances most rapidly and perfectly, while the inclosed and starved ovum is dwarfed and imperfect often to the last degree.

In many cases of excess of parts the extra part or member is manifestly derived from the same ovum, and even the same part of the ovum, being merely the effect of a redundancy and vagary of growth. Such cases include most instances of extra digits or other organs, and even of double monsters, as manifested by the fact that such extra organs grow from the normal identical organs. Hence the extra digit is attached to the normal digit, the extra head to the one neck, the extra tail to the croup, extra teeth to the existing teeth, and even two similarly formed bodies are attached by some point common to both, as the navels, breastbones, backs, etc. (Pl. XIX, figs. 1, 2, 3.) This shows that both have been derived from the same primitive layer of the embryo, which possessed the plastic power of building up a given structure or set of organs. An inclosed ovum, on the other hand, has no such ident.i.ty or similarity of structure to the part with which it is connected, showing an evident primary independence of both life and the power of building tissues and organs. The power of determining extra growth along a given natural line is very highly developed in the early embryo and is equally manifest in the mature examples of some of the lower forms of animal life. Thus a newt will grow a new tail when that member has been cut off, and a starfish will develop as many new starfishes as the pieces made by cutting up the original one. This power of growth in the embryo and in the lower form of animals is comparable to the branching out again of a tree at the places from which branches have been lopped. The presence of this vegetablelike power of growth in the embryo accounts for most double monsters.

The influence of disease in modifying growth in the early embryo, increasing, decreasing, distorting, etc., is well ill.u.s.trated in the experiments of St. Hilaire and Valentine in varnis.h.i.+ng, shaking, or otherwise disturbing the connections of eggs and thereby producing monstrosities. One can easily understand how inflammations and other causes of disturbed circulation in the womb, fetal membranes, or fetus would cause similar distortions and variations in the growing fetus. It is doubtless largely in the same way that certain mental disturbances of a very susceptible dam affect the appearance of the progeny. The monstrosities which seriously interfere with calving are mainly such as consist in extra members or head, which can not be admitted into the pa.s.sages at the same time, where some organ of the body has attained extra size, where a blighted ovum has been inclosed in the body of a more perfect one, or where the body or limbs are so contracted or twisted that the calf must enter the pa.s.sages doubled up.

_Treatment._--Extraction is sometimes possible by straightening the distorted members by the force of traction; in other cases the muscles or tendons must be cut across on the side to which the body or limbs are bent to allow of such straightening. Thus, the muscles on the concave side of a wry neck or the cords behind the shank bones of a contracted limb may be cut to allow of these parts being brought into the pa.s.sages, and there will still be wanting the methods demanded for bringing up missing limbs or head, for which see paragraphs below. In most cases of monstrosity by excess of overgrowth it becomes necessary to cut off the supernumerary or overdeveloped parts, and the same general principles must be followed as laid down in ”Embryotomy” (p. 202).

WRONG PRESENTATIONS OF THE CALF.

The following is a list of abnormal presentations of the calf:

Simultaneous presentation of twins.

A { {Limbs curved at the knee. Flexor tendons shortened.

n {Fore Limbs{Limb crossed over the back of the neck.

t { {Limb bent back at the knee.

e { {Limb bent back from the shoulder.

r { i { {Head bent downward on the neck.

o P { {Head and neck turned downward beneath the breast.

r r {Head {Head turned to one side upon the side of the neck.

e { {Head and neck turned back on the side of the chest and s { { abdomen.

e { {Head turned upward and backward on the back.

n { t { {Hind limbs rotated outward. Toes and stifles turned a { { outward.

t {Hind Limbs{Hind limbs bent forward, their feet resting in the pelvis.