Fig. [61].—a. b. c. Prostatic calculi from normal semen. d. Spermatozoa. e. Large and small cells, some containing granules, as morphological elements of semen. f. Spermatozoon distorted by imbibition of water. g. Crystals. (After Bizzozero.)
Fig. [62].—Normal semen.
If semen is left undisturbed for twenty-four hours or longer, the vitreous substance dissolves in the surrounding fluid, and this latter separates into two layers, an upper which is thinner, and a lower, which is thicker and non-transparent. In the former, the morphological elements are found but sparingly, whilst in the latter, they are plentiful. In addition to the elements already described, we find often two varieties of crystals. One of these varieties, which appears only when decomposition is far advanced, consists of ammonium magnesium phosphate. The other variety has a chemical composition not yet determined. These crystals belong to the monoclinic system, forming prisms or pyramids, often with curved surfaces; they are colourless or light yellow; they lie superimposed, often forming beautiful star-shaped figures. They are soluble in mineral and vegetable acids, and in ammonia, but are insoluble in alcohol, ether, and chloroform; they are remarkably resistent to the solvent powers of cold water, but not so to those of boiling water. Shreiner has proved that these crystals consist of a phosphate of a base which is represented by the formula C2. H5. N. According to Fürbringer, these crystals are produced as a result of the action of the semen upon the prostatic secretion.
The quantity of semen ejaculated during coitus is very variable, depending upon the age and size of the individual and the formation of his testicles, upon his individual sexual capacity, and upon the question whether antecedently there has been sexual excess on the one hand or long continued continence on the other. In general, the quantity of semen ejaculated at one time varies between 0.75 and 6 c.c. (10 to 100 minims).
If healthy, normal semen, with adequate fertilizing potency, is properly preserved from cold and light, we may, even after the lapse of twenty-four hours, find under the microscope spermatozoa still engaged in active movement. Ultzmann employs for the description of a drop of fresh semen, the comparison that it is full of movement, “like a stirred up ant-heap.” Influenced by the whiplike lashings of the tail, the spermatozoön moves steadily forwards, finding its way through the narrowest passages on the microscopic field without striking any of the cellular structures that may lie in its path. The longer the semen remains under observation, the less active are these movements of the spermatozoa, for after ejaculation they gradually die, exhibiting after death an extended, or at most a slightly curved tail; those spermatozoa, on the other hand, that were dead before ejaculation, have the tail spirally twisted, rolled up, or acutely bent. In the case of spermatozoa which have been destroyed by the action of some other deleterious secretion, as by urine or by acid vaginal secretion, such a condition of the tail is very commonly seen. When the semen is treated with water, the movements of the spermatozoa soon cease, and the ends of their tails frequently roll up to form loops. By the addition, however, of concentrated solutions of neutral salts, of albumen, of urea, etc., it is possible to reanimate these motionless spermatozoa, so that they once more are seen to perform active movements. Moderately concentrated animal secretions of an alkaline reaction are favourable to the motor activity of the spermatozoa, whilst on the other hand dilute and acid secretions, such as urine, acid mucus (including the acid vaginal mucus), and catarrhal secretions, even when alkaline in reaction, have a depressant influence on this activity. Caustic potash and caustic soda stimulate the movements of the spermatozoa. When they are cooled down to a temperature below 15° C. (59° F.), the movements cease entirely. Salts of the heavy metals, and mineral acids in solution, also bring their movements to a pause. Frequent repetition of coitus causes a diminution in the number and in the motor activity of the spermatozoa.
Semen which contains no spermatozoa, or in which the spermatozoa are motionless, is absolutely devoid of fertilizing power; in the case of such semen, it makes no difference whatever that the external genitals of the man generating it are strongly formed, that his testicles are of normal size, and that erection and ejaculation take place promptly. Of very little value, though not absolutely sterile, is semen containing very few living spermatozoa, or, among very numerous motionless spermatozoa, containing a few only that are engaged in active movement. Suspect, is semen which does not possess the normal light greyish white tint, but is brownish-red, brownish-yellow, yellow, or violet; these variations in colour indicating an admixture with the semen of varying quantities of blood or pus, in consequence of disease of the urethra, the prostate, the seminal vesicles, or some other part of the uropoietic system; such admixtures seriously impair the quality of the semen. An unfavourable judgment must also be passed on semen which, at each successive ejaculation, is voided in very small quantities only—from half a drachm to a drachm. When thus scanty, semen is often found to contain an exceptionally large proportion of dead spermatozoa. We may regard very favourably semen which is voided in quantities considerably in excess of the average; sometimes, when there is a veritable polyspermia, there may be an ounce or upwards, more than three times as much as normal—provided, of course, that this semen so richly voided is of a satisfactory quality, and contains an ample proportion of active spermatozoa. The most valuable characteristic in semen is exhibited when the spermatozoa it contains are not only very numerous and vigorously active, but when they are also very long-lived, when, that is to say, they retain the power of active movement sometimes for as long as three days. A decisive opinion as to the quality of a man’s semen can be given only as the result of precise and repeated microscopic examinations, and the medical man must be most careful, when in his first examination he has not been able to detect the presence of any living spermatozoa, to abstain from giving, on that account alone, an adverse decision—from pronouncing sentence of death on the man’s reproductive potency.
It has not hitherto been accurately determined how long spermatozoa can continue to live in the interior of the uterus, although the point is of great importance, not only in relation to conception, but also in regard to the theory of menstruation. Percy has published a case in which, eight and a half days after the last coitus, he saw living spermatozoa emerge from the os uteri externum. Sims bases upon his own researches the decisive opinion that in the vaginal mucus, spermatozoa can never survive longer than twelve hours, but states that in the mucus of the cervical canal they can live much longer. If thirty-six to forty hours after coitus, we examine the cervical mucus under the microscope, we commonly find living and dead spermatozoa in about equal numbers. Many of the living ones will survive their removal from the cervix for as much as six hours longer.
Of especial interest are the conditions which are liable to deprive a man of the power to produce fertilizing semen. In the first place must be mentioned congenital absence of both testicles—a condition which, in otherwise normally formed male individuals, is one of extreme rarity. Congenital absence of one testicle is less rare, and is usually accompanied by absence also of the epidydimis, vas deferens, and seminal vesicle of the same side. The potentia gestandi of a monorchid depends upon the proper development of his single testicle, and the functional capacity of this organ must be ascertained by a careful microscopic examination of his semen. Much more frequent than absence of the testicle, though still sufficiently rare, is the condition of cryptorchism, non-descent of one or both testicles, a state not necessarily associated with functional incapacity of the organ. Most commonly, however, an undescended testis is an imperfectly developed testis, and in the very great majority of cases the ejaculated fluid contains no spermatozoa.
A further cause of the lack of potent semen is atrophy of the testicles with notable diminution in the size of the glands, and more or less complete disappearance of the seminiferous tubules and their cellular contents. This state is rarely congenital, being nearly always acquired: in consequence of inflammatory conditions affecting the testicle proper or the epididymis (syphilitic inflammation, especially, is apt to lead to overgrowth of the interstitial connective tissue and to gradual destruction by pressure of the seminal tubules)[[46]]; or in consequence of the pressure of a hernia, a varicocele, a hydrocele, or a tubercular, carcinomatous, or other new growth; or in consequence of constitutional disorders, especially long-lasting, severe, and exhausting diseases, such as diphtheria, diabetes, or chronic alcoholism; in consequence of diseases affecting that portion of the central nervous system from which the nerves supplying the genital organs arise; in consequence of degenerative changes resulting from sexual excesses; or, finally, in consequence of senile changes, such as fatty changes in the cells of the seminiferous tubules. Certain drugs also, digitalis, salicylic acid, mercury, iodide of potassium, arsenic, and morphine, have an unfavourable influence alike on the quality of the testicular secretion and on the potency of the individual. Von Gyurkovechky reports that in Bosnia a plant locally known as “neven” is employed among the peasantry for the temporary suppression of sexual potency, wives giving it to their husbands when the latter are about to leave them and go upon a journey, and sprinkling the leaves of the plant among the underclothing.