[Footnote: Mr. Owen states that the Chimpanzee alone, amongst brute animals, has the tunica vaginalis as a distinct sac.]
Plate 39—Figure 3
PLATE 40, Fig. 1.—The abdomino-scrotal serous lining remains continuous at the internal ring, and a congenital hydrocele is formed.—When the serous spermatic tube, 6 b, 6 c, remains pervious and continuous above with the peritonaeum, 6 a, and below with the serous tunica vaginalis, 6 d, the serous fluid of the abdomen will naturally gravitate to the most depending part—viz., the tunica vaginalis; and thus a hydrocele is formed. This kind of hydrocele is named congenital, owing to the circumstance that the natural process of obliteration, by which the peritonaeum becomes separated from the tunica vaginalis, has been, from some cause, arrested. [Footnote 1] As long as the canal of communication, 6 b, 6 c, between the tunica vaginalis, 6 d, and the peritonaeum 6 a, remains pervious, which it may be throughout life, this form of hydrocele is, of course, liable to occur. It may be diagnosed from diseased enlargements of the testicle, by its transparency, its fluctuation, and its smooth, uniform fulness and shape, besides its being of less weight than a diseased testis of the same size would be. It may be distinguished from the common form of hydrocele of the isolated tunica vaginalis by the fact, that pressure made on the scrotum will cause the fluid to pass freely into the general cavity of the peritonaeum. As the fluid distends the tunica vaginalis, 6 c, 6 d, in front of the testis, this organ will of course lie towards the back of the scrotum, and therefore, if it be found necessary to evacuate the fluid, the puncture may be made with most safety in front of the scrotum. If ascites should form in an adult in whom the tunica vaginalis still communicates with the peritonaeal sac, the fluid which accumulates in the latter membrane will also distend the former, and all the collected fluid may be evacuated by tapping the scrotum. When a hydrocele is found to be congenital, it must be at once obvious that to inject irritating fluids into the tunica vaginalis (the radical cure) is inadmissible. In an adult, free from all structural disease, and in whom a congenital hydrocele is occasioned by the gravitation of the ordinary serous secretion of the peritonaeum, a cure may be effected by causing the obliteration of the serous spermatic canal by the pressure of a truss. When a congenital hydrocele happens in an infant in whom the testicle, 5, Fig. 1, Plate 39, is arrested in the inguinal canal, [Footnote 2] if pressure be made on this passage with a view of causing its closure, the testicle will be prevented from descending.
[Footnote 1: The serous spermatic tube remains open in all quadrupeds; but their natural prone position renders them secure against hydrocele or hernial protrusion. It is interesting to notice how in man, and the most anthropo-morphous animals, where the erect position would subject these to the frequent accident of hydrocele or hernia, nature causes the serous spermatic tube to close.]
[Footnote 2: In many quadrupeds (the Rodentia and Monotremes) the testes remain within the abdomen. In the Elephant, the testes always occupy their original position beneath the kidneys, in the loins. Human adults are occasionally found to be “testi-conde;” the testes being situated below the kidneys, or at some part between this position and the internal inguinal ring. Sometimes only one of the testes descends to the scrotum.]
Plate 40—Figure 1.
PLATE 40, Fig. 2.—The serous spermatic canal closes imperfectly, so as to become sacculated, and thus a hydrocele of the cord is formed.—After the testicle, 7, has descended to the scrotum, the sides of the serous tube, or lining of the inguinal canal and cord, 6 b, 6 c, may become adherent at intervals; and the intervening sacs of serous membrane continuing to secrete their proper fluid, will occasion a hydrocele of the cord. This form of hydrocele will differ according to the varieties in the manner of closure; and these may take place in the following modes:—1st, if the serous tube close only at the internal ring, 6 a, while the lower part of it, 6 b, 6 c, remains pervious, and communicating with the tunica vaginalis, 6 d, a hydrocele will be formed of a corresponding shape; 2nd, if the tube close at the upper part of the testicle, 6 c, thus isolating the tunica vaginalis, 6 d, while the upper part, 6 b, remains pervious, and the internal ring, 6 a, open, and communicating with the peritonaeal sac, a hydrocele of the cord will happen distinct from the tunica vaginalis; or this latter may be, at the same time, distended with fluid, if the disposition of the subject be favourable to the formation of dropsy; 3rd, the serous tube may close at the internal ring, form sacculi along the cord, and close again at the top of the testicle, thus separating the tunica vaginalis from the abdomen, and thereby several isolated hydroceles may be formed. If in this condition of the parts we puncture one of the sacs for the evacuation of its contents, the others, owing to their separation, will remain distended.
