frontal fontanel, or the bregma. It is of various size in different specimens. When the ossification is precocious, it is small; in the contrary case it is large, and sometimes it is found to be very large.

At the posterior terminus of the sagittal suture is found the posterior fontanel, often called the occipital fontanel.

There is a very great difference between the anterior and posterior fontanels; the former being quite large, quadrangular, and yielding to the pressure of the finger; the latter being so small that it can only be distinguished by the three suture lines that radiate from a common centre. Let the Student carefully learn to make this discrimination; for, if he should not do so, he will in practice find himself embarrassed in his diagnosis of the two fontanels.

Too much care can hardly be bestowed upon the mastering of these two points; nor can one become too familiarly acquainted with the differences between them; for, in trying to ascertain the precise position of any head-presentation, the accoucheur always seeks to place his index finger upon one or the other of these openings. It is clear that they must serve as points of departure in an exploration-for, if the index finger be in contact with the posterior fontanel, and the place that finger occupies in reference to any fixed point in the pelvis be well understood, the surgeon ought thence to deduce the very place of any and every other part of the cranium of the foetus. To know where the fontanel is, is to know where to conduct the hand, the forceps, the perforator, or the crotchet.

It has been seen, in a preceding page, that the various positions. assumed by the head when it presents in labors are enumerated as first, second, &c., and that they are determined by reference to the point on the pelvis to which the posterior fontanel is addressed.

Presentations.-The Student who shall have made himself master of the subject of the pelvic diameters is now enabled to appreciate the differences that arise in labors exhibiting various presentations and positions of the head. He knows that the bi-parietal circumference of the head is not too great to admit of its ready transition through the excavation—and he as clearly understands that the occipito-frontal or the occipito-mental circumference would prove too large for the canal. Therefore, in any case of delay or difficulty, he would provide for effecting a coincidence of the bi-parietal circumference with the planes (of the excavation) through which it must necessarily pass.

If the pelvis be only four inches in its antero-posterior diameter at the superior strait, the occipital pole of the occipito-frontal diameter

must dip so as to allow the vertex to descend, and thus become the presenting part. In fact, the foetus lies so packed up in the womb that it is truly said to be in a state of universal flexion-the legs being bent upon the thighs, the thighs upon the trunk, and the arms and forearms and whole spinal column in flexion-so that even the head is found to be flexed on the neck as a normal condition of the fœtus in utero.

The form of the flexed foetus is like that of an olive. One pole being directed to the fundus, and the other to the os uteri, gives thus two distinct, primary presentations-one cephalic, and the other pelvic, as shall be more clearly shown by and by. The drawing exhibits very naturally the usual presentation and

Fig. 31.

position of a child at the beginning of a labor. It represents the womb opened, with the foetus in what is called a vertex presentation in the first position; i. e., the posterior fontanel is turned towards the left acetabulum of the mother's pelvis, and the vertex, or occipital pole of the cranium, dips sufficiently to allow of its entering the pelvis through the plane of the superior strait.

The drawing also shows how very much the spinal column is curved. It is manifest that, if pressure should be made upon the pelvic extremity of the column,

in a direction from above downwards, it would be still more considerably bent-it would be an elastic resisting arch, and the outward thrust of the cervical extremity of that arch would tend to flex the head, more and more, in proportion to the increasing violence of the thrusting effort, so that the lower the head descends, the more must the chin be pressed against the breast, and the more perfect the coincidence of the bi-parietal circumference with the planes of the excavation through which it happens to be passing.

Unfortunately, the occipital extremity of the occipito-frontal diameter does not always dip, and the frontal extremity of it is sometimes found to be the dipping pole. In such an instance, the chin is said to depart from the breast, and we discover a presentation of the crown of the head, of the forehead, or even of the face, the head in the last

named case becoming completely extended, instead of descending in flexion. But the account of these accidents must be deferred until we come to treat of those special presentations, which we hope to be able fully to explain and describe.

The child at full term is about nineteen inches in length. Specimens are occasionally met with of children twenty-one inches high; but they are rare.

The average weight of a new-born child is somewhat above seven pounds; very many of them weigh eight pounds; and it is by no means a rare occurrence to find a child weighing nine, ten, eleven, and twelve pounds at birth.

I have never seen one yet that weighed fourteen pounds. The largest one I have weighed was thirteen pounds and a half avoirdupois. The mother soon afterwards perished with inflammation of the womb and bowels. To witness the birth of such a monster is appalling. I have heard of children of seventeen, and even of eighteen pounds' weight at birth. Such relations always lead me to suppose that some mistake has occurred in weighing the infant. M. Velpeau shrewdly remarks that children of that weight are children of three months old, and that such magnitude is impossible at birth. My own clinical experience, which has been very abundant, has never enabled me to see a child of fourteen pounds' weight at birth.

The head of the child exceeds, in its smallest circumference, the cir.cumference of the thorax and shoulders, of the abdomen or the hips: wherever the head can pass, there will, therefore, be space for the transmission of the natural body.

The length of the child, folded up in the womb in flexion, is about eleven inches from the summit of the head to the lower extremity of the pelvis or buttocks.

In about forty-nine out of fifty cases of pregnancy, the head is at the os uteri-in one out of fifty cases, the pelvis is at the os uteri, giving us the breech, feet, or knee presentation.

When the head presents in labor, it is to be supposed that it has presented during the entire gestation, and vice versâ.

The vulgar notion that the child lies in the womb with its head to the fundus until labor is about to commence, and then turns its head downwards to the mouth of the organ, in order to escape head-foremost, is erroneous-for the child is eleven inches long, and cannot turn itself in a womb only seven or eight inches in conjugate diameter. If, in like manner, the breech presents in labor, we infer that it has presented for many months antecedent to the commencement of the parturient efforts: cross presentations are rare events.

Hippocrates said the child packed up is in shape like an olive in a narrow-necked flask: if one or the other pole of the olive presents itself at the aperture, it may escape; otherwise, it must be turned or broken, or the flask must be broken, in order to extract it.

The same is true in midwifery. Either the cephalic or the pelvic pole of the foetal oval must descend, in order to its birth; and it is a matter of little moment which should be the pole, whether the cephalic or the pelvic, all other things being equal.

Upon the whole, the head presentation is the most favorable for both mother and child, since nature provides that its frequency shall be in the ratio of forty-nine to fifty.

Two Presentations only-Cephalic and Pelvic.-Rigorously speaking, there are but two presentations in midwifery: one of the head, Fig. 31; the other of the pelvis, Fig. 33. The idea expressed in the word Presentation, is one relative to the part of the foetus that comes to the opening; while the idea conveyed by the word Position, refers to some relation betwixt a cardinal point on the walls of the pelvis, and a cardinal point on the presenting part. Thus, in the pelvis, the cardinal point is always the left acetabulum—on the head, the cardinal point is the vertex or the chin. On the breech, the cardinal point is the sacrum of the foetus. For the shoulder presentation, the cardinal point is the whole head of the child.

As to the head presentation-it may deviate, and allow a shoulder to come to the os uteri: but this is a mere accident of a cephalic presentation: an accident that has arisen from the impinging of the head upon the margin or brim of the pelvis, whence it has glanced upwards to the iliac fossa, permitting the shoulder to take its place. This is to

Fig. 32.

be seen by inspecting the cut, in which the child's head, which originally presented, has deviated, and gone above the plane of the superior strait, lodging itself in the left iliac fossa, while the shoulder has come to the strait, and allowed the arm to prolapse.

The cut may serve to show how the hand and arm have merely prolapsed; making what is commonly denominated an arm presentation: but is it not clear, the head having gone up, that the shoul der still really presents, and that the arm has only fallen down or prolapsed?

From the above, it appears that we have―

1st. Cephalic presentations;

2d. Cephalic presentations deviated, with descent of the shoulder; and, lastly,

3d. Cephalic presentations deviated, with descent of the shoulder, and prolapse of the arm.

Here is a drawing representing a breech presentation, or presentation of the pelvic extremity of the foetal oval. This is the second normal presentation of the child, the cephalic

being the first. In this case, an accidental deviation might cause the buttock to glance upwards on the brim of the pelvis, to take its lodgment in the left iliac fossa. Such an accident would give rise to a footling labor, or to a pre

sentation of the knees.

A footling presentation, then, is only an accident happening in the course of a pelvic presentation-and the same may be said of the knee cases, which are very rarely met with.

I recommend these views of presentations to the Medical Student, who, if

Fig. 33.

he should adopt them, will find his notions of midwifery greatly simplified, and his memory not loaded with useless divisions and descriptions that serve only to embarrass him as a student and perplex him as a scholar or practitioner. These are the divisions I have proposed in my public lectures; and, having found them convenient also at the bedside, I with confidence advise him to prefer them to the long catalogue of presentations in the books. Knowledge in its nature is simple, pure, not complex; it owes its seeming complexity and abstruseness only to man.

If the Student should ask me where I will place the presentations of the belly or the back of the foetus, I cannot inform him, for I do not know whether they be derived from deviations of the pelvis or from deviation of the head. I am sure, however, that all such cases are accidents either of the cephalic or of the pelvic presentation, which is the essential point.

Positions of a Presentation.-The word position, as I said, refers to a relation between a certain cardinal part of the presentation, and a certain cardinal part of the pelvis. Thus, in vertex presenta