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erection. The same effect is caused still more readily by injecting the cavernous vein.
Attached to the corpora cavernosa of the penis, and running in the groove beneath them, is a spongy body, of a similar structure,—the corpus spongiosum urethræ,—through which the urethra passes. It commences, posteriorly, at the bulb of the urethra, already described under the Secretion of Urine, and terminates, anteriorly, in the glans, which is, in no wise, a dependency of the corpora cavernosa, but is separated from them by a portion of Btheir outer membrane; so that erection may take place in one and not simultaneously in the other; and injections into the corpora cavernosa of the one do not pass into those of the other. The glans appears to be the final expansion of the A. External membrane or sheath of the penis.-B. Corpus cavernosum.-D. Corerectile tissue which surrounds the ure- pus spongiosum urethra. thra. The posterior circular margin of the glans is called the corona glandis, and behind this is a depression called the cervix, collum or neck. Several follicles exist here, called the glandulæ odoriferæ Tysoni, which secrete an unctuous humour, called the smegma præputii, which often accumulates largely, where cleanliness is not attended to.
The penis is covered by the skin, which forms, towards the glans, the prepuce or foreskin. The cellular tissue that unites it to the organ is lax, and never contains fat. The inner lamina of the prepuce being inserted circularly into the penis, some distance back from the point, the glans can generally be denuded, when the prepuce is drawn back. The under and middle part of the prepuce is attached to the extremity of the glans by a duplicature, called the frænum præputii, which extends to the orifice of the urethra.
The skin is continued over the glans, but it is greatly modified in its structure, being smooth and velvety, highly delicate, sensible, and vascular.
Lastly. In addition to the acceleratores urinæ, the transversus perinei, the sphincter ani, and the levator ani muscles, which we have described as equally concerned in the excretion of urine and semen, the erector penis or ischio-cavernosus muscle is largely connected with the function of generation.
The genital organs of man are, in reality, merely an apparatus for a glandular secretion, of which the testicle is the gland; the vesiculæ seminales are supposed to be the reservoir; and the vas deferens and urethra the excretory ducts;—the arrangement which we observe in the penis being for the purpose of conveying the secreted fluid into the parts of the female.
The sperm or semen is secreted by the testicles from the blood of the spermatic artery, by a mechanism, which is no more understood than that of secretion in general. When formed it is received into the tubuli seminiferi, and passes along them to the epididymis, the vas deferens, and the vesiculæ seminales, where it is generally conceived to be deposited, until it i9 projected into the urethra, under the venereal excitement. That this is its course is sufficiently evidenced by the arrangement of the excretory ducts, and by the function which the sperm has to fulfil. De Graaf, however, adduces an additional proof. On tying the vas deferens of a dog, the testicle became swollen, and ultimately the vas deferens gave way between the testicle and the ligature.
The causes of the progression of the sperm through the ducts are, the continuity of the secretion by the testicle, and a contraction of the excretory ducts themselves. These are the efficient
It has been a question with physiologists, whether the secretion of the sperm is constantly taking place, or whether, as the function of generation is accomplished at uncertain intervals, the secretion may not likewise be intermittent. It is impossible to arrive at any positive conclusion on this point. It would seem, however, unnecessary for the secretion to be operated at all times; and it is more probable, that when the vesiculæ seminales are emptied of their contents, during coition, a stimulus is given to the testes by the excitement, and they are soon replenished. This, however, is more and more difficult in proportion to the number of repetitions of the venereal act, the excretory ducts becoming more and more emptied, whilst the secretion takes place at best but slowly.
By some, the spermatic and pampiniform plexuses have been regarded as diverticula to the testes during this intermission of action.
The sperm passes slowly along the excretory ducts of the testicle, owing partly to the slowness of the secretion, and partly to the arrangement of the ducts, which, as we have seen, are remarkably convoluted, long, and minute.
The use of the vesiculæ seminales has been disputed. The majority of physiologists regard them to be reservoirs for the sperm, and to serve the same purpose as the gall-bladder in the case of the bile. Others, however, have supposed, that they secrete a fluid of a peculiar nature, the use of which may probably be to dilute the sperm. They are manifestly not essential to the function, as they do not exist in all animals. The dog and cat kind, the bears, opossums, sea-otter, seals, &c., possess them not; and there are several in which there is no direct communication between the duct and the vas deferens, which open separately into the urethra. This circumstance, however, with the fact, that they generally contain, after death, a fluid of different appearance and properties from those of the sperm, with the glandular structure which their coats seem
to possess in many instances, is opposed to the views that they are simple reservoirs for the semen, and favours that which ascribes to them a peculiar secretion. Where this communication between the duct of the vesicles and the vas deferens does exist, a reflux of the semen may take place, and an admixture between the sperm and the fluid secreted by them. It is not improbable, however, as Adelon suggests, that all the excretory ducts of the testicle may act as a reservoir; and in the case of animals, in which the vesiculæ are wanting, they must possess this office exclusively. If we are to adopt the description of Amussat as an anatomical fact, the vesiculæ themselves are constituted of a convoluted tube, having an arrangement somewhat resembling that which prevails in the excretory ducts of the testis.
But how, it has been asked, does it happen, that the sperm, in its progress along the vas deferens, does not pass directly on into the urethra by the ejaculatory duct, instead of reflowing into the spermatic vesicles? This, it has been imagined, is owing to the existence of an arrangement at the opening of the ejaculatory duct into the urethra similar to that which prevails at the termination of the choledoch duct in the duodenum.
It is affirmed, by some, that the prostate exerts a pressure on the ductus ejaculatorius, and that the opening of the duct into the urethra is smaller than any other part of it; by others, that the ejaculatory ducts are embraced, along with the neck of the bladder, by the levator ani, and consequently, that the sperm finds a readier access into the duct of the vesiculæ seminales.
The sperm is of a white colour, and of a faint smell, which, owing to its peculiar character, has been termed spermatic. It is of a viscid consistence, of a saline, irritating taste, and appears composed of two parts, the one more liquid and transparent, and the other more grumous. In a short time after emission, these two parts unite and the whole becomes more fluid. When examined chymically, the sperm appears to be of an alkaline, and albuminous character. Vauquelin analyzed it and found it to be composed,in 1000 parts, of water, 900; animal mucilage, 60; soda, 10; calcareous phosphate, 30. Berzelius affirms that it contains the same salts as the blood along with a peculiar animal matter. No analysis however, has been made of the sperm as secreted by the testicle. The fluid examined has been the compound of the pure sperm and the secretions of the prostate gland and of those of CowThe thicker, whitish portion, is considered to be the secretion of the testicles;—the more liquid and transparent consisting of the fluids of the accessory glands or follicles.
Some authors have imagined, that a sort of halitus or aura is given off from the sperm, which they have called the aura seminis, and have considered to be sufficient for fecundation. The fallacy of this view will be exhibited hereafter. Others have discovered, by the microscope, numerous minute bodies in the sperm,
which they have conceived to be important agents in generation. These animalcules, however, have been denied to be peculiar to this fluid, and have been regarded as infusory animalcules, similar to those met with in all animal infusions; by others, they have been esteemed organic molecules of the sperm; whilst Virey,—a physiologist, strangely fantastic in his speculations,—conceives, that as the pollen of vegetables is a collection of small capsules, containing within them the true fecundating principle, which is of extreme subtlety, the pretended spermatic animalcules are tubes containing the true sperm, and the motion we observe in them is owing to the rupture of the tubes.
The agency of the sperm in fecundation will be considered hereafter. It may be observed, however, that in all examinations of it, whether by the microscope or otherwise, we must bear in mind the caution to which we have adverted more than once as applicable to the examination of animal fluids in general,—that we ought not to conclude, positively, from the results of our observations of the fluids when out of the body, that they possess precisely the same characteristics when in it; and this remark is especially applicable to the sperm, which varies manifestly in its sensible properties in a short time after it has been excreted.
The sperm being the great vivifying agent,—the medium by which life is communicated from generation to generation,—it has been looked upon as one of the most important if not the most important of animal fluids; and hence it is regarded, by some physiologists, as formed of the most animalized materials, or of those that constitute the most elevated part of the new being—the nervous system.
The quantity of sperm secreted cannot be estimated. It varies according to the individual, and to his extent of voluptuous excitement, as well as to the degree of previous indulgence in venereal pleasures. Where the demand is frequent, the supply is larger; although, when the act is repeatedly performed, the absolute quantity at each copulation may be less.
2. Genital Organs of the Female.
The genital organs of the male effect fewer functions than those. of the female. They are inservient to copulation and fecundation only. Those of the female, in addition to parts which fulfil these offices, comprise others for gestation, and lactation.
The soft and prominent covering to the symphysis pubis—which is formed by the common integuments, elevated by fat, and, at the age of puberty, covered by hair,—is called the mons veneris. Below this, are the labia pudendi or labia majora, which are two large soft lips, formed by a duplicature of the common integuments, with adipous matter interposed. The inner surface is smooth, and studded with sebaceous follicles. The labia commence at the sym
physis pubis, and descend to the perineum, which is the portion of integument, about an inch and a half in length, between the posterior commissure of the labia and the anus. This commissure is called the frænum labiorum or fourchette. The opening between the labia is the vulva.
At the upper junction of the labia, and within them, a small organ exists, called the clitoris, which greatly resembles the penis. It is formed of corpora cavernosa, and is terminated, anteriorly, by the glans, which is covered by a prepuce, consisting of a prolongation of the mucous membrane of the vagina. Unlike the penis, however, it has no corpus spongiosum, or urethra attached to it; but is capable of being made erect by a mechanism similar to that which applies to the penis, and has two erector muscles—the erectores clitoridis,—similar to the erectores penis.
From the prepuce of the clitoris, and within the labia majora, are the labia minora or nymphæ, the organization of which is similar to that of the labia majora. They gradually enlarge as they pass downwards, and disappear when they reach the orifice of the vagina.
A singular variety is observed in the organization of those parts amongst the Bosjesmen or Bushmen, the tribe to whose peculiarities of organization we have already had occasion to refer. Discordance has, however, prevailed regarding the precise nature of this peculiarity, some describing it as existing in the labia, others in the nymphæ, and others, again, in a peculiar organization; some deeming it natural, others artificial. Dr. Somerville, who had numerous opportunities for observation and dissection, asserts, that the mons veneris is less prominent than in the European, and is either destitute of hair, or thinly covered by a small quantity of a soft, woolly nature; that the labia are very small, so that they seem at times to be almost wanting; that the loose, pendulous, and rugous growth, which hangs from the pudendum, is a double fold; and that it is proved to be the nymphæ, by the situation of the clitoris at the commissure of the folds, as well as by all other circumstances; and that they sometimes reach five inches below the margin of the labia; Le Vaillant says nine inches.
Cuvier examined the Hottentot Venus, and found her to agree well with the account of Dr. Somerville. The labia were very small; and a single prominence descended between them from the upper part. It divided into two lateral portions, which passed along the sides of the vagina to the inferior angle of the labia. The whole length was about four inches. When she was examined, naked, by the French Savans, this formation was not observed. She kept the tablier, ventrale cutaneum, or, as it is termed by the Germans, schurze, carefully concealed, either between her thighs, or yet more deeply; and it was not known, until after her death, that she possessed it.