early age, as between thirty and forty years, or it may continue far beyond the average time, even up to sixty years; and exceptional, though perhaps hardly reliable, instances are recorded, in which it has continued even to eighty or ninety years. These are, however, strange anomalies, which, like cases of unusually precocious menstruation, cannot be considered as having any bearing on the general rule. Most cases of so-called protracted menstruation will be found to be really morbid losses of blood depending on malignant or other forms of organic disease, the existence of which, under such circumstances, should always be suspected.

In England menstruation usually ceases between forty and fifty years of age. Raciborski says that the largest number of cases of cessation are met with in the forty-sixth year. It is generally said that women who commence to menstruate when very young cease to do so at a comparatively early age, so that the average duration of the function is about the same in all women. Cazeaux and Raciborski, whose opinion is strengthened by the observations of Guy in 1500 cases,' think, on the contrary, that the earlier menstruation commences the longer it lasts, early menstruation indicating an excess of vital energy which continues during the whole childbearing life. Climate and other accidental causes do not seem to have as much effect on the cessation as on the establishment of the function. It does not appear to cease earlier in warm than in temperate climates. The change of life is generally indicated by irregularities in the recurrence of the discharge. It seldom ceases suddenly, but it may be absent for one or more periods, and then occur irregularly; or it may become profuse or scanty, until eventually it entirely stops. The popular notions as to the extreme danger of the menopause are probably much exaggerated; although it is certain that at that time various nervous phenomena are apt to be developed. So far from having a prejudicial effect on the health, however, it is not an uncommon observation to see an hysterical woman, who has been for years a martyr to uterine and other complaints, apparently take a new lease of life when her uterine functions have ceased to be in active operation; and statistical tables abundantly prove that the general mortality of the sex is not greater at this than at any other time.

1 Med. Times and Gaz., 1845.

PART II.

PREGNANCY.

CHAPTER I.

CONCEPTION AND GENERATION.

Generation in the human female, as in all mammals, requires the congress of the two sexes, in order that the semen, the male element of generation, may be brought into contact with the ovule, the female element of generation.

The Semen.-The semen secreted by the testicle of an adult male is a viscid, opalescent fluid, forming an emulsion when mixed with water, and having a peculiar faint odor, which is attributed to the secretions which are mixed with it, such as those from the prostate and Cowper's glands. On analysis it is found to be an albuminous fluid, holding in solution various salts, principally phosphates and chlorides, and an animal substance, spermatin, analogous to fibrin. Examined under a magnifying power of from 400 to 500 diameters, it consists of a transparent and homogeneous fluid, in which are floating a certain number of granules and epithelial cells, derived from the secretions mixed with it, and certain characteristic bodies, the spermatozoa, which are developed from the sperm cells, and which form its essential constituents. The sperm cells are those occupying the tubuli seminiferi of the testicle. Several kinds of sperm cells are described, which receive their name from the position they occupy with regard to the lumen of the tubule (Fig. 44). The cells which are next to the wall of the tubule are called the outer or lining cells. They are more or less flattened in form, and are situated on a distinct basement membrane. Internal to this layer is another, consisting of round cells, the nuclei of which are in a state of proliferation; this is the intermediate layer. Between this and the lumen of the tubule are a number of cells, irregular in shape, amongst which are imbedded the heads of the spermatozoa, the tails of which project into the lumen. The spermatozoa are thought to arise from the middle or proliferating laver in the following manner: the nuclei of the sperm cells proliferate, and from their subdivisions arise the heads of the spermatozoa, the bodies of which originate from the protoplasm of the cells. By the decomposition of the substance in which the heads of the spermatozoa are imbedded, the contained spermatozoa become liberated, and move about freely in the seminal fluid.

96

As seen under the microscope, the spermatozoa, which exist in healthy semen in enormous numbers, present the appearance of minute particles, not unlike a tadpole in shape. The head is oval and flattened, measuring about 6 of an inch in breadth, and attached to it by a short intermediate portion is a delicate filamentous expansion or tail, which tapers to a point so fine that its termination cannot be seen by the highest powers of the microscope. The whole spermatozoon measures from too of an inch in length. The spermatozoa are observed to be in constant motion, sometimes very rapid, sometimes more gentle, which is supposed to be the means by which

Section of parts of three seminiferous tubules of the rat. a. With the spermatozoa least advanced in development. b. More advanced. c. Containing fully-developed spermatozoa. Between the tubules are seen strands of interstitial cells and lymph spaces. (From a preparation by MR. A. FRAZER.)

they pass upward through the female genital organs. They retain their vitality and power of movement for a considerable time after emission, provided the semen is kept at a temperature similar to that of the body. Under such circumstances they have been observed in active motion from forty-eight to seventy-two hours after ejaculation, and they have also been seen alive in the testicle as long as twentyfour hours after death. In all probability they continue active much longer within the generative organs, as many physiologists have observed them in full vitality in bitches and rabbits, seven or eight days after copulation. The recent experiments of Haussman, however, show that they lose their power of motion in the human vagina within twelve hours after coitus, although they doubtless retain it longer in the uterus and Fallopian tubes. Abundant leucorrhoeal discharges and acrid vaginal secretions destroy their movements, and may thus cause sterility in the female. On account of their mobility, the spermatozoa were long considered to be independent animalcules, a view which is by no means exploded, and has been maintained in

modern times by Pouchet, Joulin, and other writers, while Coste, Robin, Kölliker, etc., liken their motion to that of ciliated epithelium. There can be no doubt that the fertilizing power of the semen is due to the presence of the spermatozoa, although some of the older physiologists assigned it to the spermatic fluid. The former view, however, has been conclusively proved by the experiments of Prévost and Dumas, who found that on carefully removing the spermatozoa by filtration the semen lost its fecundating properties.

Sites of Impregnation.-There has been great difference of opinion as to the part of the genital tract in which the spermatozoa and the ovule come into contact, and in which impregnation, therefore, occurs. Spermatozoa have been observed in all parts of the female genital organs in animals killed shortly after coitus, especially in the Fallopian tubes, and even on the surface of the ovary. The fact that fecundation has been proved to occur in certain animals within the ovary, tends to support the idea that it may also occur in the human female before the rupture of the Graafian follicle. In order to do so, however, it is necessary for the spermatozoa to penetrate the proper structure of the follicle and the epithelial covering of the ovary, and no one has actually seen them doing so. Most probably the contact of the spermatozoa and the ovule occurs very shortly after the rupture of the follicle, and in the outer part of the Fallopian tubes. Coste maintains that, unless the ovule is impregnated, it very rapidly degenerates after being expelled from the ovary, partly by inherent changes in the ovule itself, and partly because it then soon becomes invested by an albuminous covering which is impermeable to the spermatozoa. He believes, therefore, that impregnation can only occur either on the surface of the ovary, or just within the fimbriated extremity of the tube.

Mode in which the Ascent of the Semen is Effected.-The semen

is probably carried upward chiefly by the inherent mobility of the spermatozoa. It is believed by some that this is assisted by other agencies amongst them are mentioned the peristalti action of the uterus and Fallopian tubes; a sort of capillary attraction effected when the walls of the uterus are in close contact, similar to the movement of fluid in minute tubes; and also the vibratile action of the cilia of the epithelium of the uterine mucous membrane. The action of the latter is extremely doubtful, for they are also supposed to effect the descent of the ovule, and they can hardly act in two opposite ways. The movement of the cilia being from within outward, it would certainly oppose rather than favor the progress of the spermatozoa. It must, therefore, be admitted that they ascend chiefly through their own powers of motion. They certainly have this power to a remarkable extent, for there are numerous cases on record in which impregnation has occurred without penetration, and even when the hymen was quite entire, and in which the semen has simply been deposited on the exterior of the vulva; in such cases, which are far from uncommon, the spermatozoa must have found their way through the whole length of the vagina. It is probable, however, that under ordinary circumstances the passage of the spermatic fluid into the uterus is facilitated.

by changes which take place in the cervix during the sexual orgasm, in the course of which the os uteri is said to dilate and close again in a rhythmical manner.'

Impregnation. The precise method in which the spermatozoa effect impregnation was long a matter of doubt. It is now, however, certain that they actually penetrate the ovule, and reach its interior. This has been conclusively proved by the observations of Barry, Meissner, and others, who have seen the spermatozoa within the external membrane of the ovule in rabbits (Fig. 45). In some of the invertebrata a canal or opening, called the micropyle, exists in the zona pellucida, through which the spermatozoa pass. No such aperture has yet been demonstrated in the ovules of mammals, but its existence is far from improbable. According to the observations of Newport, several spermatozoa penetrate the zona pellucida and enter the ovule, and the greater the number that do so the more certain fecundation becomes. In the lower animals the fusion of the spermatozoa with the substance of the yelk has been observed, and although similar phenomena have not been detected in the human ovum, there is not any doubt but that the further development of the ovum is due to the union of the spermatozoa with the female element.

FIG. 45.

The length of time which elapses before the fecundated ovule arrives in the cavity of the uterus has not yet been ascertained, and it probably varies under different circumstances. It is known that in the bitch it may remain eight or ten days in the Fallopian tube, in the guinea-pig three or four. In the human female the ovum has never been discovered in the cavity of the uterus before the tenth or twelfth day after impregnation.

Imme

Ovum of rabbit containing spermatozoa. 1. Zona pellucida. 2. The germ, consisting of two large cells, several smaller cells, and spermatozoa.

The changes which occur in the human ovule immediately before and after impregnation, and during its progress through the Fallopian tube, are only known to us by analogy, as, of course, it is impossible to study them by actual observation. We are in possession, however, of accurate information of what has been made out in the lower animals, and it is reasonable to suppose that similar changes occur in man. diately after the ovule has passed into the Fallopian tube, it is found to be surrounded by a layer of granular cells, a portion of the lining membrane of the Graafian follicle, which was described as the discus proligerus. As it proceeds along the tube these surrounding cells disappear, partly, it is supposed, by friction on the walls of the tube, and partly by being absorbed to nourish the ovule. Be this as it may, before long they are no longer observed, and the zona pellucida forms the outermost layer of the ovule. When the ovule has advanced some distance along the tube, it becomes invested with a covering of albu

1 "How do the Spermatozoa Enter the Uterus?" By J. Beck, M.D.