Upon Mucous Membranes, and especially upon that of the urinary bladder, there occurs a cancerous growth which we have elsewhere termed villous cancer, as a structure pertaining to medullary carcinoma, and containing within a villo-membranous vascularized stroma, a medullary (encephaloid) cancer juice. Later investigations have led to results which induce me to reopen this subject.

It consists, as a walnut- or a fist-sized tumor, of a multitude of densely thronged excrescences, which, upon a cord-like, longer or shorter, pedicle unfold into delicate membranes, breaking up into numerous ramifications, and again into more and more tender branchlets, wholly overlaid with delicate villi. Many twigs have a grape-clustered appearance, their villi bearing poppy or millet-seed-like, clear or opaque, white vesicles. Larger cysts reside in the primary cotyledon and ramification. Many excrescences, again, represent hollow, shut, or at their free extremity, wide-mouthed pouches. In one instance, the entire growth consisted of polyedrical, at their free ends for the most part wide-' mouthed, pouches, densely beset with villi at the brink of the aperture. The tumor is throughout surcharged with a whitish, creamy, medullary juice. It is frequently a more consistent medulla-like mass that fills up the cavities of the growth, which in this case acquires considerable density, and offers proportionate resistance.

The growth is in general highly vascular, and in its recent state, turgid, of a deep purple tint, and prone to hemorrhage. At the base, from whence the tumor commonly rises with a neck, we have found an extensive sinus of a venous kind, upon the inner surface of which are seen numerous pin-puncture and poppy-seed-sized orifices, leading to bloodvessels, which ascend within the pedicles of the excrescences, and accompany their ramifications.

In the vicinity of, or even remote from, the heterologous structure, are smaller groups, or solitary excrescences. These, when young, are very delicate, so as when under water to resemble a fine nap.

Microscopic Examination

In the cream- or marrow-like juice that exudes on gentle pressure, are found variously-shaped cells, with one or several, in part turgid, vesicle-like nuclei, along with bare, middle-sized, and larger-sized nuclei, furnished with a considerable nucleus-corpuscle, of which one especially, was found large, and presenting internally a dull secondary nucleus contour. This juice resides in the before-mentioned pouch-like chambers. The excrescences are externally clothed with an epithelial layer.

The membranous structure constituting the excrescence appears as a very delicate, transparent, structureless, here and there striated membrane, overstrewn with oblong nuclei, and breaking forth about the pedicle into slender wavy fibrils. It is invested with a simple layer of granulated nuclei for epithelium, which is, however, frequently wanting.

A clustered twig appears as a clavate, hollow structure upon a delicately fibred pedicle, young cysts, as structureless vesicles, occupying the interior of the protuberances. Here are seen two outlines, of which the outer one belongs to the protuberance, the inner one to the young cyst; elongated nuclei course along between the two. The cyst is replete with spherical nucleolated nuclei. A few cysts open towards the pedicle of the terminal bulb in which they are contained.

In some of these sacculi are besides found, in various numbers up to the point of repletion, fat-globules, some of largish dimensions. These lend to the cyst the white opaque aspect already referred to.

The larger millet-seed-sized vesicles, visible to the naked eye, contain a colorless, tenacious fluid in which the above-mentioned nuclei float.

A morsel of a membranous expansion of the excrescence appears, when magnified by 50 diameters, distinctly to consist of two layers, and is everywhere, but especially at the summit, overspread with numerous bulb-shaped protuberances, which themselves throw out secondary projections; whilst considerable bloodvessels ascend to all. In the inside are here and there seated groups of fat-globules.

Their bilaminated structure renders it more than probable that the layers, in consequence of the copious production and accumulation of 'the cancerous elements, separate into the pouches aforesaid, which, for the same reason, give way at this free extremity.

In 1842, a urinary bladder was shown to us by Hodgkin, at Guy's Hospital, upon the inner surface of which were seated numerous largish bulb-shaped cysts, filled with the excrescences referred to.

The extensive development of the cysts in a mucous membrane is in itself very remarkable; whether, with the excrescences, they be of a cancerous nature appears uncertain. Upon the mucous membrane of the renal pelvis we have seen, along with young cysts, some solitary, others grouped together in its parenchyma, awl-shaped and bulbous, smooth and villous, red, vascular excrescences. They were seated, in part singly, partly in collected groups, some bearing a just discernible transparent globule at their free extremity, which microscopic examination showed to be a young cyst.