The entrance of pigment into the composition of any cancer converts it into cancer melanodes. Nowhere, however, does this substance occur in so marked a degree as in a cancer closely resembling the medullary. It may indeed be said, that cancer melanodes (so-called malignant melanosis) is but a medullary carcinoma modified by pigment, an idea promulgated by Meckel, von Walther, and others, in their day.

Cancer melanodes, as an independent tumor, presents most of the physical aspects of medullary carcinoma. Its cut surface appears to the naked eye either homogeneous, or fibrous, or lobulated, and of a more or less firm and brain-like consistence. A closer inspection of it reveals elementary granules, nuclei, cells of spherical or oval, caudate, elongated, angular shape, and along with these the most varied intercellular substances and stromata. Melanotic cancer imitates most commonly the encephaloid variety of medullary carcinoma, with round and caudate cells, and a membranous - a villo-membranous - stroma.

These alien growths are chiefly marked by their black or brown-black, brown, bronze-green, or rust-brown coloration. The first glance at these often numerous tumors generally suffices to show that the color is merely accessory. For, amongst thoroughly tinged, we meet also with perfectly colorless, white, heterologous growths; and again between the two extremes others pigmented in the most various forms, in dotted or stellate patches, or in ramifying anastomosing strise. The white growths are recognized at once as genuine, ordinary, encephaloid cancer.

A minute examination detects, according to circumstances, a greater or lesser proportion of pigment, and, even in the blackest, elements enough - cells and intercellular substance - free from pigment.

Pigment occurs free or inclosed in cells, in all the forms enumerated under that heading. Its basis is, as there taught, and especially as the examination of acutely produced or redundantly growing cancer mela-nodes incontestably proves, hsematin in a free and dissolved state, or else blood-globules, with their pigment, in substance. In the latter case, the alien growth resembles a hemorrhagic effusion, in which are found along with the blastema the elements of medullary cancer in various phases of coloration and of conversion into pigment.

Chemical analysis must needs detect the constituents of medullary carcinoma, and the pigment with its base. Barruel and Henry have discovered, in the melanosis in man, hsematin, fibrin, three kinds of fat, a considerable amount of phosphate of lime, and iron.

Like medullary carcinoma, cancer melanodes is found to infiltrate the textures of parenchymata, as also of membranous parts, the dura mater for instance.

By reason of its pigment, melanotic cancer may be studied at its outset in very small point-like portions, which* under a magnifying power, appear minutely ramified.

Like genuine medullary cancer, the melanotic often attains to an extraordinary circumference. Its simultaneous occurrence in many, if not in most organs, is, however, still more usual. Its multiplication is often very rapidly brought about, with the concurrence, it may be, of acute typhoid fever. No organ is exempt from the disease. Even when attacking all, or several, organs simultaneously, it may grow inordinately in a single one or more than one, in which case the liver is almost always found to be the organ of predilection. We have seen it in the brain and about the nerves, at the eyeball, in the lungs, in the thyroid gland, in the liver, spleen, kidneys, bones, lymphatic glands, ovaries, in and beneath the intestinal mucous membrane, between the mesenteric layers, in the skin and subcutaneous areolar tissue, upon serous membranes, in the dura mater, upon and within the heart.

In the majority of cases, cancer melanodes is found to affect middle-aged or still older individuals. Both we ourselves and others have however observed it with little less of frequency even in youth.

The crasis upon which cancer melanodes is based, is without doubt essentially the medullary. The pigment has, however, still to be accounted for. A special dyscrasial character of the hasmatin and of the blood-globules might here suggest itself, a crasis analogous to the constitution of the portal blood with a continuous excess of aged and spent blood-globules which have reached their climax of coloration in a defibri-nated plasma, the ready suscipient of hsematin. Such a view would find support in the cachexia so often concurrent with melanosis, and so characteristic of a predominant venous constitution, with a vivid, brownish coloration of the common integuments. And to this might be added the fact, that cancer melanodes is more than ordinarily rich in pigment when occurring in the liver and the choroid plexus, in which, for various ends, pigment is thrown out from the spent blood-globules even in the physiological state.

But, apart from numerous exceptions in this last respect, we must guard against overlooking very important local processes in cancer melanodes, where the base of the pigment. is furnished, not by the general circulation, not by haematin, but by substantive blood-globules. Here the question is, first, whence is derived the blood as the basis of pigment? and, secondly, what causes the transmutation of the blood to pigment? The latter question is the more pertinent that in medullary carcinoma hemorrhage is common enough without any entailment of the pigment of cancer melanodes. In reply to the first query, we have to express a well-substantiated conviction that the blood furnishing the base of the pigment in cancer melanodes is not - at least not mainly - an ex-travasate out of a perfected system of bloodvessels; but blood newly formed in parent-cells, and transformed into pigment either within these cells or upon their breaking up.

This metamorphosis within parent-cells engaged in a process of radiation and ramification into a capillary system, explains the circumstance that the pigment, in its first manifestation in the parenchyma of a genuine white medullary carcinoma, appears in the form of finely branched and stellate points and patches.

Cancer melanodes generally proves fatal in its excessive, multiple production, through the exhaustion and wasting corresponding to such redundant alien growth. In rare instances cancer melanodes enters upon a process of ulceration, and kills through hemorrhage or simple exhaustion.