time, according to the particular conditions of the female and fœtus, in different individuals, and in the same individual in different labours. The parts, however, when once dilated, yield much easier afterwards to similar efforts, so that the first labour is generally the most protracted.

After the separation of the secundines, the female is commonly left in a state of debility and fatigue; but this gradually disappears. The uterus also contracts; its vessels become tortuous, small, and their orifices are plugged up. For a short time blood continues to be discharged from them; but as they become obliterated by the return of the uterus to its usual size, the discharge loses its sanguineous character, and is replaced by one of a paler colour, called the lochia, which gradually disappears, and altogether ceases in the course of two or three weeks after delivery.

For a day or two after delivery coagula of blood form in the interior of the uterus, especially in the second and subsequent labours, which excite the organ to contraction for their expulsion. These contractions are accompanied with pain, and are called after-pains: as their object is the removal of that which interferes with the return of the uterus to its proper dimensions, it is obvious that they ought not to be officiously interfered with.

Whilst the uterus is contracting its dimensions, the other parts gradually resume the condition they were in prior to delivery; so that in the course of three or four weeks, it is impracticable to pronounce positively, whether delivery has recently taken place or not.

Fig. 147.

Labour, as thus accomplished, is more deserving of the term in the human female than in animals; and this is partly owing to the large size of the foetal head, and partly to the circumstance, that in the animal the axis of the pelvis is the same as that of the body, whilst in the human female, the axis of the brim, as represented by the dotted straight lines in Fig. 146, forms a considerable angle with that of the outlet.

The position of the child, exhibited in Fig. 144,-with the face behind and the occipital before,-constitutes the usual presentation in natural labour. Of twelve thousand six hundred and thirty-three children, born at the Hospice de la Ma

ternité of Paris, twelve thousand one hundred and twenty, accord

ing to M. JULES CLOQUET, were of this presentation; sixty-three had the face turned forward; one hundred and ninety-eight were breech presentations; (see Fig. 147;) in one hundred and forty-seven cases the feet presented; and in three the knees. All these, however, are cases, in which labour can be effected without assistance; the knee and feet presentations being identical, as regards the process of delivery, with that of the breech. But whenever any other part of the foetus . presents, the position is unfavourable, and requires that the hand should be introduced into the uterus, with the view of bringing down the feet, and converting the case into a foot presentation. The details of this subject, however, belong more appropriately to obstetrics.

When the child has been separated from the mother, and continues to live by the exercise of its own vital powers, it has still to be dependent upon her for the nutriment adapted to its tender condition. Whilst in utero this nutriment consisted of fluids placed in contact with it, but, after birth, a secretion serves this purpose, which has to be received into the stomach and undergo the digestive process. This secretion is the milk. It is prepared by the mammæ or breasts, the number, size, and situation of which are characteristic of the human species. Each breast contains a mammary gland, surrounded by the fat of the breast, and resting on the pectoralis major muscle. It is formed of several lobes, united by a somewhat dense, cellular tissue, and consisting of smaller lobules, which seem, again, composed of round granulations, of a rosy-white colour, and of about the size of a poppy seed. The glandular granula give origin to the excretory ducts, called tubuli lactiferi or galactophori, which are tortuous, extensible, and transparent. These enlarge and unite with each other, but so that those of each lobe remain distinct from, and have no communication with, the ducts of any other lobe. All these finally terminate in sinuses, near the base of the nipple, which are fifteen or eighteen in number, and open on the nipple, without having communication with each other.

The size and shape of the breast are chiefly caused by the cellular tissue in which the mammary gland is situated: this is covered by a thin layer of skin, which is extremely soft and delicate, and devoid of folds. In the middle of the breast is the tubercle, called the nipple,-a prominence consisting of an erectile spongy tissue, differing in colour from the rest of the breast,—and around it is the areola, which is of a rosy hue in youth, but becomes darker in the progress of life, and the capillary system of which is so delicate as to blush, like the countenance, under similar emotions. The changes, produced on the areola by gestation, have been already described. The skin, at the base of the nipple, and on its surface, is rough, owing to the presence of a number of sebaceous follicles, which secrete a fluid for the lubrication of the part, and for defending it from the action of the saliva of the infant during lactation. Numerous arteries, veins, nerves and lymphatics,-the anatomical

constituents of organic textures in general,-also enter into the composition of the mammæ and nipples.

The secretion of milk is liable to longer intermissions than any other function of the kind. In the unmarried and chaste female, although the blood, whence milk is formed, may be constantly passing to the nipple, no secretion takes place from it. It is only during gestation and for some time afterwards, that the necessary excitation exists to produce it. Yet although largely allied to the generative function, the mammæ undergoing their chief development in puberty and becoming shrivelled in old age,-the secretion may arise independently of impregnation; for it has been witnessed in the unquestionable virgin, in the superannuated female, and even in the male sex. The fact as regards the unimpregnated female is mentioned by HIPPOCRATES. BAUDELOCQUE states, that a young girl at Alençon, eight years old, suckled her brother for the space of a month. Dr. GORDON SMITH refers to a manuscript in the collection of Sir HANS SLOANE, which gives an account of a woman, at the age of sixty-eight, who had not borne a child for more than twenty years, and who nursed her grandchildren, one after another; and Dr. FRANCIS, of New York, describes the case of a lady, who, fourteen years previously, was delivered of a healthy child after a natural labour. "Since that period," he remarks, "her breasts have regularly secreted milk in great abundance, so that, to use her own language, she could at all times easily perform the office of a But these, and cases of a similar nature, of which there are many on record, do not possess the same singularity as those of the function being executed by the male. Yet we have the most unquestionable authority in favour of the occurrence of such instances. The Bishop of Cork relates a case in the Philosophical Transactions for 1741, of a man who suckled his child after the death of his wife. HUMBOLDT adduces one of a man, thirty-two years of age, who nursed his child for five months on the secretion from his breasts; and Captain FRANKLIN, in his "Journey to the shores of the Polar Sea," gives a similar instance.

nurse."

It appears, therefore, that the secretion of milk may be caused, independently of a uterus, by soliciting the action of the mammary glands, but that this is a mere exception to the general rule, according to which the secretion is as intermittent as gestation itself.

We have noticed, as one of the signs of pregnancy, that the breasts become enlarged and turgid, denoting the aptitude for the formation of the fluid; and it not unfrequently happens that, towards the middle and latter periods of pregnancy, milk will distil from the nipples. This fluid, however, as well as that which flows from the breasts during the first two or three days after delivery, differs somewhat from milk, containing more serum and butter, and less caseum, and it is conceived to be more laxative, so as to aid the expulsion of the meconium. This first milk is called colostrum, protogala, &c., and, in the cow, constitutes the biestings or beastings. VOL. II.

43

Generally, about the third day after confinement, the mamma become tumid, hard, and even painful, and the secretion from this time is established, the pain and distention soon disappearing.

It is hardly necessary to discuss the views of RICHERAND, who considers the milk to be derived from the lymph; of others who derive it from the chyle; or of GIRARD of Lyons, who gratuitously asserts, that there is in the abdomen an apparatus of vessels,-intermediate between the uterus and mammæ,-which continue inactive, except during gestation, and for some time after delivery, but, in those conditions, are excited to activity. All these notions are entirely hypothetical, and there is no reason for believing, that this secretion differs from others, as regards the kind of blood from which it is separated. The separation takes place in the tissue of the gland, and the product is received by the lactiferous ducts, along which it is propelled by the fresh secretion continuously arriving, and by the contractile action of the ducts themselves, the milk remaining in the ducts and sinuses, until the mammæ are, at times, considerably distended and painful.

The excretion of the milk takes place only at intervals. When the lactiferous ducts are sufficiently filled, a degree of distention' and uneasiness is felt, which calls for the removal of the contained fluid. At times, the flow occurs spontaneously; but, commonly, only when solicited either by sucking or drawing the breast, the secretion under such circumstances being very rapid, and the contraction of the galactophorous ducts such, as to project the milk through the orifices in a thready stream.

Milk is a highly azoted fluid, composed of water, caseum, sugar of milk, certain salts,-as the muriate, phosphate, and acetate of potassa, with a vestige of lactate of iron and earthy phosphate,and a little lactic acid. According to BERZELIUS, it consists of cream, and milk properly so called,-the cream consisting of butter, 4.5; cheese, 3.5; whey, 92.0;-and the whey of milk and salt, 4.4;-the milk containing, water, 928.75; cheese, with a trace of sugar, 28.01; sugar of milk, 35.00; muriate of potassa, 1.70; phosphate of potassa, 0.25; lactic acid, acetate of potassa, and lactate of iron, 6.00; and phosphate of lime, 0.30.

Human milk contains more sugar of milk and less cheesy matter than that of the cow; hence it is sweeter, more liquid, less coagulable, and incapable of being made into cheese. Its quantity and character differ according to the quantity and character of the food,a circumstance, which was one of the great causes of the belief, that the lymphatics convey to the mammæ the materials for the secretion. The milk is, however, situated in this respect like the urine, which varies in quantity and quality, according to the amount and kind of solid or liquid food taken. The milk is more abundant, thicker, and less acid, if the female lives on animal food, but possesses the opposite qualities when vegetable diet is used. It is apt, also, to be impregnated with heterogeneous matters, taken up from the digestive canal. The milk and the butter of cows indicate un

equivocally the character of their pasturage, especially if they have fed on the turnip, wild onion, &c. Medicine, given to the mother, may in this way act upon the infant.

The quantity of milk secreted is not always in proportion to the bulk of the mammæ; a female whose bosom is of middle size often secreting more than another in whom it is much more developed;the greater size being usually owing to the larger quantity of adipous tissue surrounding the mammary gland, and this tissue is in nowise concerned in the function.

The secretion of milk usually continues until the period, when the organs of mastication of the infant have acquired the necessary development for the digestion of solid food: it generally ceases during the second year. For a great part, or the whole of this time, the menstrual flux is suspended; and if both the secretions,-mammary and menstrual-go on together, the former is usually impoverished and in small quantity. Whilst lactation continues, the female is less likely to conceive; and hence the importance,-were there not even more weighty reasons,-of the mother's suckling her own child, in order to prevent the too rapid succession of children. When menstruation recurs during suckling, it is an evidence that the womb is again fit for impregnation.

OF FETAL EXISTENCE.

The subject of foetal existence forms so completely a part of the function we are considering, that its investigation naturally succeeds to that of the part performed by the parents in its production; and especially as the development of the foetus is synchronous with all the uterine changes that have been pointed out. By most writers on physiology it has been the custom to include this subject under the same head as gestation, but the anatomy and physiology of the fœtus have recently been so much studied as to sanction their separation.

Anatomy of the Foetus.

The uncertainty, which hangs over the immediate formation of the new individual, has been already mentioned; and it is not necessary for us to do more than refer to the description of the different views regarding the predominance of the paternal or maternal influence over the character of the product of generation. The microscopical observations of Mr. BAUER, under the superintendance of Sir EVERARD HOME, would seem to show, that the human ovum and that of the quadruped consist of a semitransparent, elastic, gelatinous substance, enveloped in two membranous coverings; that this substance is formed in the ovarium independently of the male influence, but requires the application of such influence to undergo its developments.

The period, at which the embryo is first perceptible in the