Hydrocele of the tunica vaginalis.—The sac of the tunica vaginalis, like other serous ca vities, is liable to dropsical effusion. The fluid effused is usually transparent, and of an amber, pale yellow, citron, or straw co lour, and resembles the serum of the blood, but is occasionally thick. According to Dr. Marcet's analysis#, 1000 grains of this fluid of the specific gravity 1024 3 contained 80 grains of solid matter, of which 715 con sisted of animal, and 85 of saline ingredients hence it appears that this fluid only differs from the serum of the blood in possessing rather less animal matter. In an analysis of the fluid of hydrocele made by Dr. Bos tockt, 10000 parts of the specific gravity 102i were found to contain ferent structure from that of the cellular tissue, the extension of inflammation inwards is checked. Thus, in the case of the inflamed tunica vaginalis, the cellular tissue readily transmitted the morbid action to the epididy mis, but the tunica albuginea arrested its progress to the body of the testicle ; and this explains the fact that after inflammation of the tunica vaginalis, excited by injection, the body of the gland is rarely found to suffer. On the other hand, the epididymis is seldom attacked with inflammation without the disease being quickly propagated to the tunica vagi nalis.
The lymph effused in inflammation very often forms adhesions between the opposed serous surfaces, and these after some time are rendered very firm and dense, and in old cases are often converted into a fibro-cartilaginous structure. In a testicle which I examined some little while after an attack of acute in flammation, I found the lymph on both sur faces of the tunica vaginalis presenting a honeycomb or lace-like appearance, similar to that often met with on the pericardium. In flammation, if violent, may end in the forma tion of pus ; suppuration is, however, a rare occurrence, unless artificially excited, for the cure of hydrocele. Inflammation of the tunics vaginalis is not only the most frequent disease of the testicle, but it is also one of the most common affections to which the body is liable.
A quantity of flakey matter or flocculent albumen is sometimes found floating in the fluid ; and it frequently contains, especially in old people, cholesterine in the form of a multitude of minute shining particles. The quantity of cholesterine contained in nine teen ounces of dark fluid full of these shining particles, which I removed from an old hy drocele, amounted to nine grains. In the examination of a testicle from a man of co lour who died at an advanced age, I found the tunica vaginalis and its investing tissues very thick and firm, and the seat of cartilaginous and osseous deposits; it contained about three drachms of a thick brownish substance, which was almost entirely composed of cholesterine. This was no doubt a very old case of hydro cele, in which, the more fluid parts having been absorbed, the cholesterine was left be hind within the indurated sac. The quantity of serum which is suffered to accumulate varies considerably. In this country it seldom exceeds twenty ounces, though it has been known to amount to several pints. The largest quantity which I have met with is forty-eight ounces. Mr. Cline is said to have
removed from Gibbon the historian as much as six quarts.$ In simple hydrocele the testicle is usually found at the posterior part, and rather below the centre, of the sac: its situation however is subject to variations. Before the occur rence of hydrocele the tunica vaginalis may have been inflamed and contracted adhesions, so that the testicle may be connected to the membrane in front ; in which case the serum accumulates on each side of or above and below the organ. The position of the testicle in front may also be owing to an original inversion of the organ, in which the free sur face presenting backwards, the fluid collects in that direction and presses the testicle to the front of the sac. Sometimes there are several adhesions producing a sacculated ar rangement and forming what is termed a multilocular hydrocele. Occasionally the cysts thus formed have no communication with each other. In two instances I have seen a membranous partition in the sac of a hydro cele, separating it into two distinct cavities, formed by a layer of false membrane. There is one kind of sac or pouch often met with in hydroceles which is not commonly de scribed. It is situated on the inner side of the testicle, but the opening into it is always found on the outer side between the body of the gland and the middle of the epididymis. This sac, which varies very much in size, is formed by the distention of the cul-de-sac which I have described as existing naturally at this part. Two examples of this kind of pouch are contained in the Hunterian Mu seum. One of them is represented in the accompanying figure. In large hydroceles the epididymis is usually elongated and dis placed ; and instead of a pouch being formed, the central part of the epididymis is drawn to some distance from the body of the tes ticle. In old hydroceles the sac is often a good deal thickened, the tissues enveloping it being condensed and converted into layers of dense fascia, such as are commonly observed investing only hernial sacs. The fibres, also, of the cremaster muscle, frequently become remarkably developed. This, however, is not constantly the case ; for in some instances of hydrocele of large size I have found this muscle atrophied. The thickened sac after many years acquires a cartilaginous cha racter, and it sometimes even becomes os sified. In cases which have been frequently tapped, the sac is often found closely ad herent to the skin of the scrotum at the various points perforated by the trocar. In the Hunterian Museum there is a prepar ation showing a long narrow band of ad hesion passing from the anterior part of the testicle across the dilated sac of the tunica vaginalis to the membrane in front, which is supposed to have resulted from a wound of the testicle in the operation of tap ping. In all large hydroceles the spermatic vessels are separated and displaced. The glandular structure of the testicle is sound, and the organ capable of exercising its func tions. The disease is strictly confined to the investing serous tunic. The testicle is, how ever, frequently somewhat altered in shape, being flattened by the pressure of the confined fluid ; and in some instances has been found partially atrophied.