Effects of go along the cord between the two layers of chorion and Impregna, amnios, which cover it, into the vesicula umbilicalis. These are called omphalo-mesenteric.

tion.

33

34

35

In quadrupeds, a canal, called urachus, is continued from the urinary bladder, along the umbilical cord, and communicates with a membrane, which, like this canal, does not exist in the human subject, called allantois. The urine of the young animal is collected in that membrane.

Some anatomists, as Albinus, have imagined, that the urachus and allantois do exist in the human subject. They were deceived by the appearance of the vesicula umbilicalis and omphalo-mensenteric vessels.

The liquor amnii is never in such proportion to the fœtus in the latter, as in the early periods of pregnancy. It is less pure too at that period, being often polluted with the stools of the fœtus. Except in this circumstance, its chemical qualities are the same.

We shall now offer a few observations on the changes which have been described.

1. The cause of the increase of growth in the uterus is very obscure. The accession of fluids will account for the phenomenon; but a strong objection occurs against considering that as the cause, i. e. that the uterus increases to a certain degree in size, even although the direction of fluids be to another part, as where the fœtus is extra-uterine. Boehmerus has marked this very accurately in a case of extra-uterine conception, which he has detailed (A). The developement of its fibres seems to prove, that the increase of size depends on a certain energy of the uterus itself; perhaps this may appear a very ambiguous mode of expression, yet we can offer no other explanation of this curious phenome

non.

2. The great bulk of the uterus during the latter months, sufficiently explains the cause of the various complaints which occur at that period. Van Doeveren has described this very accurately. He says, "uteri gravidi incrementum, adscensus è pelvis cavo, et immanis expansio, innumeros excitat gravidarum morbos; primo quidem arctando abdomen, et mechanicè comprimendo viscera quæ in eo continentur, hepar, lienem, ventriculum, intestina, omentum, nec minus partes iis vicinas, nempe, renes, ureteres, aortam, venam cavam, arterias et venas iliacas, nervosque è medulla spinali prodeuntes inferiores; accidit pectoris coarctatio, similesque effectus inde excitati in corde, pulmonibus vasisque majoribus; ex quibus multiplici modo circulatio, digestio, chylificatio et respiratio læduntur, inque tota corporis œconomia, ejusque functionibus ingentis, solent produci turbæ variaque vitia topica excitari, inter quæ, tensiones, spasmi, dolores, stupores, obturationes, obstructiones, inflammationes, congestiones, præ cæteris memorabiles sunt; unde nascitur magna series morborum abdominis, pectoris, ipsiusque capitis; nec non artuum inferiorum VOL. XIV. Part I.

torpores, dolores, crampi, œdemata, erysipelata, varices, Effects of hæmorrhagia, ulcera, labiorum vulvæ inflationes, varia- Impregnaque vitia partium genitalium, et alia multa pro diversa partium compressarum aut distentarum actione, variis nominibus insignienda (B)."

3. The origin of the membrane, which appears about the third month, called by Dr Hunter membrana de. cidua reflexa, has afforded matter of dispute among physiologists. Dr Hunter imagined, that the decidua vera consisted of two layers, and that the ovum, enve-loped in chorion and amnios, got somehow between these: but this is a very unsatisfactory opinion. The more probable opinion is, that the decidua vera and decidua reflexa are distinct membranes, although both formed in the same manner. If, as we have already stated, the uterus, soon after conception, be filled with a gelatinous fluid, and if the ovum be in contact with that organ at one point only, then it is probable that the vessels of the internal surface of the uterus, by shooting into the fluid with which it is covered, will form one membrane, the decidua vera; while the vessels on the external surface of the chorion, will shoot into the fluid with which the ovum must have been covered in its descent, and form another membrane, the decidua reflexa.

In proof that both membranes are formed in this way, it may be observed, that where the fœtus is extrauterine, the uterus is lined with the decidua vera, and there is no decidua reflexa.-Boehmer is the first who demonstrated this; and not Dr Hunter, as has been alleged. He says, "Quum vero uterus magnitudine gravido unius circiter mensis similis videretur, eundem posterius longitudinaliter, et superius transversaliter dissecuimus, inque ejus cavo, intuitu haud impregnati satis magno, nihil præter tenacem et flavescentem mucum, mollemque poroso-villosam et valvulosam quasi turgescentem membranam undique uteri parictes et tubas investentem, hinc inde inflammatam et erosam, structuram autem uteri satis compactam invenimus *."

tion.

36

* Bochmer

37

4. The formation of the placenta is a curious subject loc. cit. of inquiry. That it depends principally on the foetus, P. 27. is proved by the appearances in extra-uterine conceptions. In the case of ventral conception, published by Mr Turnbull of London, this circumstance is very clearly pointed out (c).

39

menta,

cause lib. xxix. sect. 3. § 9.

P.

39

40

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6. Since from the situation of the foetus it has no direct communication with the atmospheric air, two questions occur on the subject; first, whether it be necessary that the foetus should receive the vivifying somewhat which the natus receives from the atmosphere. 2dly, If this be answered in the affirmative, by what means is this somewhat furnished?

1. On looking into the works of Nature, we find that there is a class of animals placed in a similar situation with the foetus, viz. the locomotive fishes. These receive the vivifying somewhat furnished by the atmosphere through the medium of the fluid in which they are immersed; for their blood is always distributed by the smallest ramifications over a substance in constant contact with the water, before it return into the arterial system to serve for the purposes of nutrition.

From analogy therefore it must be allowed, that the fœtus does receive, through some means or other, the vivifying principle of the atmosphere.

2. By what means then is this furnished? Many cir cumstances concur to prove that it is by means of the placenta. For,

Ist, The structure of the placenta resembles much. that of the lungs. It is cellular, and has the whole blood of the foetus distributed in the smallest branches over its substance. See ANATOMY, ANIMAL, Chap. 4. SUPPLEMENT.

2dly, The blood returning from the placenta is sent by the nearest possible means to the left side of the heart. And, 3dly, Compression of the umbilical cord to such a degree as to interrupt the circulation through it, destroys the fœtus as soon as compression of the trachea does the natus.

It appears therefore that the placenta serves to the foetus the same purpose which lungs do to the natus.

The celebrated Haller has objected to this probable "Non use of the placenta in the following words. pauci etiam auctores secundis pulmonis officium tribuerunt, cum in vena umbilicali sanguis ruber sit et floridus, si cum sanguinis sodalis arteriæ comparetur. Idexperimentum mea non confirmant. In pullo arteria fere In fætu humano nunquam coccinea, vena violacea est. floridum sanguinem vidi; neque intelligo ut placenta, in qua certissime nulla sint aerea mutabiles vesiculæ *Haller. possit pulmonis munere fungi *."

loc. cit. lib.

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But later observations have contradicted the assertions xxix sect. 3. of Haller on this occasion. In particular, Dr Jeffray, $37. professor of anatomy in the university of Glasgow, in an inaugural dissertation published here in the year 1786, relates an experiment made by him which is "Puero completely opposite to the opinion of Haller. "he says" in obstetricatoris sinu jacenti, funiculus tribus vinculis circumjectis, et simul in arctum tractis colligatus est; quo dein juxta umbilicum inciso, in arteriis umbilicalibus et venis, inter duo vincula placentum proxime, sanguinis copia interceptum est. Intercepti spatii vasa, gelatinosa funiculi parte cultro dempta, in conspectum venerunt; et arteria, quæ sangui

nem jam ante in parte circumlatum, ad placentam per- Natural ferebat, puncta est; quam prope arteria puncturam Parturition vena quoque umbilicalis similiter puncta est. Quo facto ex vena sanguis effluens, cum eo qui ex arteria effluebat facile comparari poterat. Ille, venosi sanguinis instar, nigricabat; hic, sanguinis in adulta arteriis mox vivide florebat (D)."

7. The means by which the foetus is nourished have hitherto escaped the investigation of physiologists. That the stomach and intestines do not serve this purpose is obvious from many concurrent testimonies; but particularly from these organs being on some occasions entirely wanting, while other parts of the system of the fœtus were complete. It is probable that the placenta supplies nourishment, as well as the vivifying principle of the air to the foetus in utero.

CHAP. III. Natural Parturition.

HUMAN parturition, where every thing is natural, is perhaps one of the most beautiful and interesting operations in nature; for what can be more beautiful than a process accomplished by the combined action of a num ber of powers admirably well adapted to the intended purpose; and what can be more interesting than the continuation of our species which depends on the operation?

In treating of this subject, we shall first consider the term of gestation; 2dly, the phenomena of natural parturition; and, 3dly, the causes of those phenomena.

SECT. I. Term of Gestation.

The ancients imagined that although nine kalendar months be the most usual period of human pregnancy, yet on some occasions that period may be, and actually is, protracted even beyond ten calendar months. Accordingly, it was laid down as a maxim in ancient jurisprudence, that children born within eleven months after the death. of their supposed father should be declared legitimate.

In modern times the question has been often agitated, both among medical practitioners and among lawyers. Practitioners of midwifery however have had most frequent occasion to investigate this subject, and they have differed materially in their conclusions.

Roederer says,

"Hunc terminum, finem nempe trigesimæ nons et nonnunquum quadragesimæ hebdomadis partui maturo natura, uti accuratior observatio docet constituit, ultraque eum non facile differtur. Nibil hic valet energia seminis deficiens, morbosa vel debilis patris constitutio, matris dispositio phthisica, hectica, qua foetus sufficienti alimento privatur; nihil, status matris cachecticus, fluxus menstruus tempore gestationis contingens, diarrhoea aliusve morbus; nihil nimia uteri amplitudo; nihil affectus matris vehementior, qualis tristitia; nihil diæta matris extraordinaria, vel inedia; nihil fœtus debilitas et dispositio morbosa ; nihil plures fœtus in utero detenti.

"Tantum enim abest ut hæ causæ fœtus moram in utero retardent, ut potius accelerent. Viduæ quidem vanis hisce speciebus, illicitam venerem defendere atque hereditates aucupari, quin in eo medicos nimis credulos,

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Natural dulos, vel lucri cupidos in suas partes trabere student, Parturition. sed mera hæc sunt ludibria, prætereaque nihil (E)."

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But many eminent teachers of midwifery believe that in some cases human pregnancy is protracted for two or three weeks beyond the more common period. Dr Hamilton especially says, "In the human species nine kalendar months seem necessary for the perfection of the fœtus; that is, nearly thirty-nine weeks, or two hundred and seventy-three days from conception. The term does not, however, appear to be so arbitrarily established, but that nature may transgress her usual laws; and as many circumstances frequently concur to anticipate delivery, it certainly may in some instances be protracted. Individuals in the same class of quadrupeds, it is well known, vary in their periods of pregnancy. May we not, therefore, from analogy reasonably infer, that women sometimes exceed the more ordinary period? In several tolerably well attested cases, the birth appears to have been protracted several weeks beyond the common term of delivery. If the character of the woman be unexceptionable, a favourable report may be given for the mother, though the child should not be produced till nearly ten kalendar months after the absence or sudden death of her *Outlines husband *. of Midwifery,

p. 192.

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SECT. II. Phenomena of Natural Labour. The sufferings of a woman during labour having been compared to the fatigues of a person on a journey, the phenomena of labour have been divided into three stages. The first stage consists of the opening of the mouth of the womb; the second, of the actual passage of the child; and the third, of the separation and expulsion of the secundines.

Phenomena of the First Stage. In most instances the bulk of the belly subsides for a day or two before labour begins; but the first evidence of the actual commencement of that process is the occurrence of pains in the belly affecting the loins, and striking down the thighs, occasioning considerable irritation of the bladder and bowels. These pains, &c. however, often take place during some hours of the night, for days, or even weeks, before true labour begins, and are then styled spurious pains. It is not easy on many occasions to distinguish true labour throes from spurious pains, unless the state of the mouth of the womb be examined, so very nearly do they resemble each other. But in general spurious pains recur at irregular intervals, and do not increase in force according to their duration; whereas true pains gradually recur at shorter intervals, and become more and more violent.

Spurious pains are sometimes attended with an occurrence which was first publicly noticed and described by the present professor of midwifery in the university of Edinburgh (F), viz. the protrusion of the urinary bladder. This resembles, to a superficial observer, the bag formed by the membranes which inclose the child, and in consequence has repeatedly been burst by the fingers of the operator. Incurable incontinence of urine, inflammation of the passages, &c. have followed this accident.

Protrusion of the urinary bladder may be readily Natural distinguished from that of the membranes which in- Parturition. clude the infant by two circumstances. First, the bag recedes completely during the interval of the pain; and secondly, when pushed down, the finger cannot be passed round it at the fore part of the pelvis; it seems as if fixed to the pubis. True labour-pains arise from the contractions of the womb by which that organ is shortened and thickened; and, at the same time, its contents are forced through its orifice. When they become regular and forcing, they have the effect of opening the mouth of the womb, so that a practitioner can readily ascertain the difference between them and spurious pains. The opening of the mouth of the womb, in most instances, is accompanied by the discharge of a slimy, bloody-like matter, termed shews; but in many women there is no such circumstance.

This process is generally gradual, the pains increasing in frequency and force; and eight, ten, or twelve hours, commonly elapse before they complete the opening of the womb. In some cases the dilatation takes place to a considerable extent before pains occur, so that a few pains accomplish this stage. But these exceptions are not so frequent as those of an opppsite description, where one or two complete days are required to open the womb, though the pains be unremitting.

In proportion as the first stage advances, the membranous bag containing the child is pushed through the mouth of the womb, and forced gradually into the vagina. During the pain it is tense, and during the interval it becomes relaxed. When this happens, the head of the infant can be distinctly felt behind it. At last, the passages being sufficiently opened, the pains having become stronger and more frequent, the membranes give way, and the water contained within them is discharged; which finishes the first stage. Shivering, vomiting, headach, thirst, and pain in the back, take place in many instances during this stage.

Phenomena of the Second Stage. Sometimes an interval of ease of some minutes duration succeeds the discharge of the waters. The pains then become much more violent and forcing, and the head, by the contractions of the uterus thus becoming more powerful, is pushed through the brim of the pelvis into the va gina. For this purpose the vertex is forced foremost, and the brow is turned to one sacro-iliac synchondrosis, so that the largest part of the head is applied to the widest part of the bason; for as the head is oval, and the opening through which it is to pass is of the same form, this is absolutely necessary.

After the head is in the vagina, the pains still continuing, the vertex is turned into the arch of the pubis, and the face into the hollow of the sacrum, by which the largest part of the head is brought into the direction of the widest part at the outlet. All the soft parts are now protruded in the form of a tumour, a portion of the vertex is pushed through the orifice of the vagina, and every pain advances the progress of the infant, till at last the head is expelled. An interval of a minute or two now ensues, after which another pain ta G 2

king

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This stage is in many instances extremely tedious ; but after the woman has had one child, it often is completed within the time of six or eight pains.

Phenomena of the Third Stage.-Whenever the infant is born, if there be no other in the womb, the parietes of the abdomen become relaxed, and the womb can be perceived through them, contracted almost into the size of a child's head. An interval of ease of some minutes duration now elapses, after which pains again recur, commonly attended with the discharge of some clots of blood; occasioning a kind of gurgling noise, and the placenta and membranes are thrown off, and the womb remains quite contracted or nearly so, with a cavity scarcely capable of containing a hen's egg. In some cases a single pain accomplishes this, and in others several pains are required; but, generally speaking, this stage is completed within an hour after the birth of the child.

It sometimes, however, happens that the natural ef forts are inadequate to the expulsion of the secundines. The causes are, want of sufficient contractile power in the uterus, irregular contraction of that organ, and indurated state of the placenta itself.

From the above description it is obvious that all the three stages of labour are completed by one simple power, viz. the contraction of the womb.

SECT. III. Causes of the Phenomena of Labour.

I. The first phenomenon which requires explanation is the action of the uterus. Why does that organ generally act at a certain period, after having remained in a quiescent state for so long a time?

This question bas puzzled physiologists strangely. Some have attributed the circumstance to a stimulus communicated by the foetus: but their opinion is overturned by a well-known fact, that the same phenomena occur though the foetus be dead. Others have imagined that the uterus is excited to act in consequence of previous distension. But were this the case, women should never have the uterus of a larger bulk in one pregnancy than in another; whereas, on the contrary, it is well known that women who have twins or triplets often have the womb distended to fully double the usual size.

Physiologists as well as physicians have fallen into very great errors from referring complex phenomena to a single cause. A variety of facts concur to prove, that in the present instance it is absurd to impute the action of the uterus to any single cause.

To what then should we attribute it? To a variety of circumstances.

1st, To the structure of the uterus. From the appearance of that organ in its unimpregnated state, it would seem that nature had laid up in store a certain proportion of fibres to be developed during pregnancy.

2d, It is probable, however, that in ordinary cases this store of muscular fibres is seldom entirely exhausted, from the circumstance of women having sometimes twins or triplets; some other cause therefore must concur in exciting the action of the uterus. The contents of the uterus perhaps furnish this cause.

In the latter months of gestation, some parts of the fœtus come in contact with the parietes of the uterus, in consequence of the decrease in proportion of the liquor amnii. This is principally the case with respect to the head, which presses on the cervix, and that part of the uterus, it is probable, is more irritable than any other; for we find that the entrance or exit of all hollow muscular organs is more irritable than the other parts, as we see exemplified in the cardia of the stomach, and in the cervix of the urinary bladder.

3d, It is not improbable too, that the pressure of the neighbouring parts contributes somewhat to induce the action of the uterus; for it is remarked by practitioners of midwifery, that women seldom arrive at the full period of gestation in a first pregnancy, and the parietes of the abdomen yield with difficulty at first, as is observed in cases of dropsy. Besides all farmers know well, that in every succeeding pregnancy, cows exceed their former period of gestation.

II. The next phenomenon worthy of notice is the 53 manner in which the child's head enters the pelvis. Two circumstances contribute towards this, first the connection of the head of the child with the neck; and 2dly, The form of the brim of the pelvis.

The first of these circumstances has been accurately pointed out by Dr Osborn. He says, "after the os uteri has been first opened by the membranes and contained waters, forming a wedge-like bag, the next operation and effect of the labour-pains or contractions of the uterus (for they are convertible terms) must be on the body of the child, which being united to the basis of the cranium at the great foramen and nearer the occiput than forehead, the greater pressure will be applied to the occiput, which being likewise smaller, and making less resistance, will be the first part squeezed into the cavity of the pelvis (E).”

The latter circumstance has been clearly explained by Professor Saxtorph. He remarks, " causa hujus directionis capitis, concurrente toto mechanismo perfecti partus, potissimum hæret in pelvi. Nam agente utero in fœtum, in axi pelvis locatum, caput ejus hucusque liberum, in humore amnii fluctuans, propter molam suam majorem in introitum ipso pelvis magnam resistentiam patitur à prominentia? ossis sacri, quæ in posteriori parte segmenti inferioris uteri ita impressa est, ut pro

montorii

Natural montorii instar fœtus frontem glabram, rotundam, unico Parturition puncto tantummodo illam tangentem et satis mobilem,

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* Dr Os. born, loc.

blando motu ad latus dirigat, in spatium ei exactè respondens inter protuberantiam ipsam et marginem in ternum acutum ilii excavatum, quam ob rem, sincipitis prævii sutura sagittalis cadit necessario in diametrum obliquum aperture superioris pelvis (F)."

It is remarkable, that neither of these celebrated authors discovered that a combination of both the circumstances just enumerated, is necessary to occasion the phenomenon.

Two advantages result from this position of the head of the child; for, 1st, The largest part of the head is applied to the widest part of the superior aperture; and, 2dly, The head, when the occiput is forced foremost, occupies the least possible space.

III. The phenomenon which next strikes us, is that change in the position of the head by which the face is turned into the hollow of the sacrum.

Although the advantage, and even necessity, of this change in the position of the head, has been long known to practitioners; yet Dr Osborn is, perhaps, the first author who has clearly explained the efficient cause of this. His remarks are these: "As it (viz. the head) descends obliquely through the pelvis, the pressure of the two converging ischia will not be exactly opposite to each other on the two parietal bones; but one ischium acting or pressing on the part of that bone contiguons to the occiput, and the other on the opposite side next to the face, the head being made up of different bones, united by membranes, and forming various sutures and fontanels, which permit the shape to be changed, and the volume to be lessened, it necessarily follows, that the head, thus compressed, will take a shape nearly resembling the cavity through which it passes; and, as from the convergency of the ischia, the cavity of the pelvis somewhat approaches the form of a cone, the child's head is moulded into that shape, the shape of all others best adapted to open the soft parts, and make its way through the os externum.

This un

equal pressure of the two ischia upon the head, will, in the first instance, direct the occiput, or apex of the cone, to turn under the arch of the pubis, where there is little or no resistance; while the pressure of the other ischium, in its further descent, will have the same effect on the other side, and direct or compel the face to turn into the hollow of the sacrum *."

This change of position is productive of three advan

cit p. 30. tages.

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Ist, The largest part of the head is again adapted to the widest part of the pelvis.

ap

2dly, The smallest possible surface of the head is plied to the surface of the bones of the pubes. And, 3dly, As Dr Osborn, in the passage quoted, very justly observes, the head is moulded into that shape which is best calculated to pass without doing harm, through the soft parts.

IV. The phenomena which occur when the head passes through the external parts, are easily explained. After the head has made that turn, by which the face is placed in the hollow of the sacrum, the coccyx

and perinæum resist its further descent in that direc- Natural tion, and by forcing the nape of the neck against the Parturition. inferior edge of the symphysis pubis, every successive pain contributes to make the occiput rise up towards the abdomen, by which the chin leaves the top of the thorax, on which it had rested during the preceding process of delivery.

By this simple mechanism, the soft parts are gradually prepared for the passage of the child, while, at the same time, the shoulders are brought into the most favourable position for passing through the pelvis.

V. The phenomena of the third stage of labour obviously originate from the contraction of the uterus, which both separates and expels the secundines. Some authors have imagined that nature has provided for this purpose a particular apparatus, placed at the fundus uteri; but as the placenta, when attached to the cervix uteri, is thrown off as readily as when it is attached to the fundus, it is very evident that these authors have been deceived by a seeming regularity of fibres, which is sometimes observed.

Lastly, The obstacles which nature has opposed to the passage of the child, occasion all the difficulties of human parturition. These obstacles are formed by the situation and shape of the pelvis, and the structure of the soft parts concerned in parturition.

The pelvis is situated in such a direction, that its axis forms an obtuse angle with that of the body; consequently, it is not placed perpendicularly, but obliquely to the horizon; and hence nothing can pass through it by the force of gravity.

The shape of the pelvis, too, is such, that the head of the child cannot pass through the outlet in the same direction in which it entered the brim; and, from the structure of the soft parts concerned in parturition, they yield with considerable difficulty.

By these means, the Author of our existence has guarded against the effects of the erect posture of the body, and has prevented the premature expulsion of the child and the sudden laceration of the soft parts.

SECT. IV. Treatment of Natural Labour.

First stage.-When this stage proceeds naturally and regularly, there is very little else to be done, after having ascertained that labour has really begun, and that the child is in the ordinary position, than taking care that the bowels be open, and palliating any unpleasant symptoms, such as shivering or vomiting, &c. which may occur.

But if after the pains have become so regular as, by their continuance, to disturb the ordinary functions of life, that is, most commonly, after they have been quite regular for twelve or fifteen hours; if this stage be not completed, it is necessary to interfere, and to endeavour, by art, to effect the dilatation. The reason for this rule is abundantly evident. If this stage of suffering be longer protracted, the strength of the patient must be exhausted by the long-continued exertion, and, of course, the remaining process of labour cannot be completed. Hence the child may be lost, or alarming discharges

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