we conclude, it may be useful to observe, that these notions are pow. erfully supported by the observations of Mr. POWER; whilst they seem, in return, to elucidate the view he has taken of the same subject. We will now consider the essay of Dr. DEWEES; and, in the first place, the explanation he advances of the same phenomenon. He commences with remarking, that a change has obviously taken place in civilized life, by which parturition is rendered an act of difficulty and danger; and he states his object in this essay to be, "to show in what some of these changes consist, and how to ameliorate them."

The causes of difficult and painful labours, he continues to remark, may be divided into two general heads: those arising from some imperfection of the pelvis, and those which interrupt the natural and healthy functions of the soft parts. It is to the latter which his atten tion in this essay is confined.

The author, in the first instance, gives a brief account of the opinions of Dr. HUNTER, MALPIGHI, and RUYSCH, respecting the arrangement of the muscular fibres of the uterus, notices their discre pancy, and then observes, that the correctness of neither of those descriptions has been satisfactorily proved. Since then, he continues, "anatomists have never been able with their knife to clear up this point, we must have recourse to other means to satisfy ourselves: the only certain one, it appears to me, is, to deduce them from the actions of the uterus itself; this at least warrants two distinct sets, the one circular, the other longitudinal."

This, it must be well known, was the opinion of VESALIUS, though he also supposed the existence of transverse fibres.

The basis of the arguments of Dr. Dewees is by no means a valid one for such a deduction, and will not be so admitted at the present time, when physiologists are not disposed to limit the property of contractibility to muscular fibres; and it is not well ascertained that the chief actions of the uterus are expressly longitudinal, and transverse or circular. Many observations, especially those made when the placenta has been attached to unusual parts of the uterus, and when there has been two or three children in it at the same time, seem to show that like the stomach, it performs numerous varieties of action, according as it is irritated in one part or in another. Such actions are shown to take place in the stomach by the expulsion of substances from it, by vomiting, that are not adapted for digestion, whilst alimentary matter is retained.*

Let us for a time, however, admit of the supposition of Dr. Dewees, since the establishment of this forms the basis of his dissertation; and, if we do not acknowledge it, we cannot readily proceed with him in his enquiry.

Taking for granted, then, the existence of longitudinal and trans. verse muscular fibres in the uterus, the author next proceeds to state, that "he cannot help regarding the neck of the uterus as a distinct and independant part from the body and fundus, and as having its

* See our review of Dr. LALLEMAND'S Thesis in the fortieth volume of this Journal. Many curious facts of this kind are there noticed.

own peculiar laws and actions; and that this separation of powers is absolutely necessary to the explanation of some of the phenomena exhibited by health and disease, and the influence of certain agents on

these parts.

This susceptibility to diseased action cannot be well disputed, and is indeed generally admitted. Dr. Dewees next adduces a statement of all the circumstances, which he considers most concur to produce parturition with the greatest possible regularity. These are,

"First, there must be a subsiding of the abdominal tumor; and, if at this time a finger be introduced through the os tincæ, we shall find the membranes alternately tense and relaxed: these circumstances are owing to the uterus now beginning to contract, and forcing the presenting part into the pelvis.

Secondly, there must be a secretion of mucus from the vagina: in some instances this flows from it, several days previous to the onset of pains; but, for the most part, it only happens a few hours before they are felt. This mucus is secreted from the surface of the vagina, and perhaps from a portion of the neck of the uterus. Why these glands are excited to this duty may perhaps be difficult to explain, but their action appears intimately connected with a certain state or condition of the os tincæ: thus we find, cæteris paribus, this secretion to be most abundant where there is the greatest disposition in the mouth of the uterus to dilate or relax; and with this is connected the same dis. position of the perinæum. It must be observed, that the secretion here spoken of must not be confounded with leucorrhoea, as this discharge is by no means favourable to this effect.

Thirdly, the mouth of the uterus must yield easily, that the contractions of the body and fundus may not be exerted for too long a time unavailingly. The dilatation of the mouth of the, uterus, when best performed, is either before or very quickly after the painful contractions of the uterus have taken place: this, in general, is done without the mechanical aid of the contents of the uterus.

Fourthly, the body and fundus must contract with sufficient force, to make the child pass through the pelvis.

"Fifthly, the perineum must unfold without much or any mecha nical force, that the child may not be detained in passing through the

Os externum.

"Sixthly, there must obtain between the foetus and pelvis a proper proportion, and the former must be well situated, that it may derive every advantage from the circumstances just enumerated."

In his observations on the dilatation of the orifice of the uterus, we meet with nothing either novel or particularly remarkable: his chief object is to show that," in the most natural and favourable cases of labour, the mechanical power of the ovum has no influence in dilating the mouth of the uterus." This is generally admitted, and Dr. Dewees might have spared his disquisition on the description of BAUDELOQUE; for that author, in his own language, advances the same doctrine. He next considers" the different kinds of contraction of the uterus."

“First, the longitudinal contraction: this is performed by the fibres

of the uterus, so called, or those fibres which run from the fundus to the neck; it serves to shorten the uterus in the direction of these fibres; consequently, to expose is contents more and more, by making them approximate the mouth; and this will be in proportion to the diminution of resistance at this part, and the force with which these fibres may act.

"The circular contraction. This action is performed by the fibres so named; they, as it were, run round the uterus, commencing at the fundus, and terminating in the circle forming the neck; they tend to diminish the capacity of the uterus in the direction of its transverse diameter; consequently, have little or no immediate agency in expel Jing its contents.

"The simple contraction, or when either of these sets of fibres act separately, as, before labour especially, when the finger is introduced through the os tince, we find the membranes alternately tense and relaxed. In this case, we presume, the longitudinal fibres act alone, as there is no stiffening of the circle forming the mouth; or, as when the waters have been evacuated, the uterus is made to embrace its con tents, and no pain for a long time is produced; we suppose, in this instance, the circular fibres act alone, as there is no effort to expel the contents of the uterus, which would not be the case did the longitudinal fibres co-operate with them.

Compound contraction, or when both sets of fibres act. Their united action is proved, we conceive, when there is a hardening of the mouth of the uterus, and an evident depression of this viscus, with its contents, into the lower part of the pelvis.

Tonic contraction. By this we understand that uniform action which the uterus exerts to reduce itself to its original size: this appears to be the effect of all the fibres folding themselves up after the distracting cause is removed.

"The spasmodic, or that contraction of the uterus, which is for the most part accompanied with pain. It must be remembered, however, that pain does not necessarily belong to this species of contraction, since some women are delivered without it. We should therefore, agreeably to this fact, rather call this species the alternate, contraction of the uterus, as it has a greater or less interval between each con, traction. When this action is best performed, it is, we presume, chiefly by the longitudinal fibres..

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"It may here become a question," continues the author, "how are the fibres of the uterus enabled to perform this alternate contraction ? since we know that a muscle, after having contracted, cannot repeat that contraction, without being first relaxed, and then elongated." We shall not follow him in his remarks on this point; it has no direct connexion with the question under consideration, and we are desirous to give as clear and direct an exposition of his arguments in favour of his hypothesis, as his desultory manner will permit. It should be remembered, that the existence of muscular fibres in the uterus is not determined; that membranous contraction will proceed without intervals of relaxation; and that the tonic and spasmodic mode of action, which the author enumerates, seem, with the aid of the abdoNO. 247.

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minal muscles, sufficient to explain all the consequences observed in the mechanism of the act of parturition.

The author then considers "the relative strength of the different sets of fibres:" he says,

1

166 We have already observed, that the longitudinal fibres were stronger than the circular: our reasons for thinking so are,

"First, that, were they of equal strength in all parts of the uterus, delivery could not take place, since the circular fibres would embrace the body of the child, and thus retain it; their action being, as we have already said, to diminish the uterus only in its transverse diameter, consequently, is at right angles with the longitudinal.

"Secondly, that, when from any circumstance the power of the circular fibres is increased, either absolutely or relatively, there the “labour does not advance; therefore, the circular fibres are not to be considered as directly instrumental in expelling the child.

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Thirdly, as the circular fibres, from the direction of their action, do not immediately contribute to the advancement of the child, they must be considered as the weakest set, since delivery takes placé without their direct aid: the longitudinal fibres have then not only to move the child, but overcome their resistance.*

Now, let us apply these facts to the explanation of the dilatation of the uterus and the progress of labour.

"When the woman has carried her child to the full time of gestation, that process termed labour must ensue, that she may be enabled to part with it; for this purpose one part of the uterus must yield or dilate, while another must contract. The uterus is closed at bottom, and maintained in that situation by the contraction of the muscular fibres of its mouth; but these must relax, that the child may effect its escape. We must therefore regard the circular and longitudinal planes of fibres, as a kind of antagonist muscles to each other. The longitu dinal fibres yield more willingly to impulse from within the uterus than the circular during gestation, owing perhaps to their greater length, or perhaps greater laxity:+ they continue to yield until they are so much upon the stretch as to induce a disposition to contract; this they eventually do. The circular fibres, on the other hand, from their greater rigidity, most probably are put immediately upon the stretch: they therefore have a constant. stimulus to excite their contraction; hence the mouth of the uterus keeping closed. But, so soon as the longitudinal fibres become uneasy, from distention, they become `re. fractory, and will yield no more without resistance; they then con. tract, and continue to do so until the stimulus of distention becomes still more powerful, which eventually brings on the period of labour. By the contraction of the longitudinal fibres the length of the uterus diminishes this puts the circular upon the stretch, since the uterus

* This is particularly the case in the instances where the membranes are prematurely ruptured: the uterus, by virtue of its tonic contraction, accommodates itself to the various inequalities presented by the child's body, and some of these are eminently calculated to retard labour; yet the longitudinal fibres overcome them. - Hence perhaps the lengthened form of the uterus....!

cannot diminish in one direction, while the mouth of the uterus remains shut, without augmenting. In another; therefore, the circular, fibres are a little distracted, and they immediately co-operate with the longitudinal, and force the uterus, with its contents, lower into the pelvis. In this instance, what we have termed the compound action of the fibres, takes place: this is proved by the edges of the mouth of the uterus stiffening during the contraction.

"This kind of action is reciprocated for some time, but the circular fibres eventually yield to the influence of the longitudinal; first, from, their having expended a portion of their power in maintaining a state of contraction so long; and, secondly, their being absolutely the weaker fibre. Hence the circular fibres which constitute the neck relax, and hence the dilatation of the mouth of the uterus."

After some adventitious remarks on the secretion of mucus, and the yielding of the external parts, the author, proceeds to treat of "the contraction of the fundus and body of the uterus." We wholly, transcribe his observations on this subject.

"That the uterus may be enabled to expel its contents, as we haver already said, the fundus and body must contract, while the mouth must relax. We have endeavoured to show how the latter was effected; let us now, for a moment, attend to what must be done by the fundus and body, that delivery may take place.

"When the mouth of the uterus is sufficiently dilated to allow the child to pass through it, the fundus and body must continue to contract: this contraction is of two kinds, namely, the tonic, and the spasmodic or alternate. The tonic contraction is chiefly performed by the circular fibres: by this contraction the whole of the internal sur face, of the uterus is applied to the body to be moved, and the longi tudinal fibres, by this means, are brought more closely into contact with it, and of course are enabled to act with more effect. This perhaps is the chief use of the circular fibres at this period of labour; as: they do not, in any instance, directly contribute to the advancement of the child, as we have already observed, and shall now endeavour to prove more fully.

"We shall relate some circumstances attending the contraction of the uterus, which will deserve notice, and to the truth of which every accoucheur will bear testimony,

First, that a considerable degree of contraction may take place in the circular fibres without producing pain: thus, after the evacuation of the waters, and the uterus is closely applied to the body of the child, even to a degree that would render turning impracticable, yet no pain is felt.

66 Secondly, when this contraction is violent, it throws the uterus into inequalities, and sometimes divides it like an hour-glass; this obtains in a degree before the birth of the child, but more especially after it, and before the expulsion of the placenta. In these instances the contraction is obstinately maintained, but no pain is felt.

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Thirdly, if the finger be applied to the presenting part during the continuance of this contraction, it is not found to advance.

"Fourthly, when this constriction is most violent, the longitudinal