chiefly base their diagnosis of cancer. There is no form of cell growth that can be set down as peculiar to malignant disease; but we look at the multiplicity of forms presented by the new growth, and their deviation from the normal structure of the part. In other words, we consider a tumour to be of a cancerous nature, because its growth appears to have taken place uncontrolled by the formative power of the organ in which it has occurred.

But it may be objected that certain forms of malignant disease occur at an age and under circumstances in which we are not justified in assuming the previous existence of degenerative changes; when, for instance, a soft, rapidly-growing tumour follows an injury to the eye, in a child previously in apparently perfect health. The answer to this is, that other forms of degeneration may exist besides those before mentioned, and with which we are unacquainted; and that if the more frequent varieties of cancer can be shown to co-exist with degenerations, it is probable that in the rarer kinds some defect in the formative powers has been inherent in the affected parts.

When we admit the connection of cancer with degeneration of other important organs, much of the interest connected with the often-debated question of the local origin of malignant disease is lost; for, if we allow it to be a local malady, still it is one that arises from a general cause, and, therefore, merely local treatment cannot be expected to free the patient from the chance of its recurrence. Two circumstances seem to me to show that the cancerous material does not arise from an abnormal action in the part in which it is situated. First, that the discase often re-appears

CONCLUSIONS RESPECTING CANCER.

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two or three years after an operation, although during this interval no trace of it may have been discovered; and secondly, that, although in every age local remedies have been employed, and malignant growths have been extirpated in every possible manner, no one has been able to prove that he could prevent their recurrence.

I am inclined to believe that cancer arises from something allied to an animal poison, susceptible of being produced during and engendered out of the degeneration of the tissues. We have before seen that it is one of nature's ordinary plans for giving time for the recovery of the system, to deposit in some structure any animal poison that may have found entrance into the blood.' As syphilis affects the bones; scarlatina the skin and mucous membranes; tubercle the lungs and glands; so is each variety of cancer localized in that organ for which it has the greatest affinity, or which is in such a state of degeneration as to be susceptible of attack.

Other animal poisons are removed from the body, partly by ulceration, partly by resorption, and such is the case with cancers. The resorption of these poisons is apt to be followed by the reproduction of new and similar growths, and growths, and so it is in malignant disease. As the kidney is inflamed by the passage of the scarlatina poison through its tubes, as the absorbents of the groin enlarge when the venereal virus traverses them, so the glands of the axilla become affected when a malignant tumour of the breast breaks up in the course of its removal from the system.

1 See pp. 123 and 209.

U

Cancer seems to agree with tubercle in the impossibility of its passing through the ordinary emunctories of the body. Instead of being eliminated, like the scarlatina virus through the kidneys, it is retained in the system; and each breaking up of a tumour leads to the further dissemination of the disease.

The similarity between the new growths in fever and those produced in some of the forms of cancer seems to have forcibly impressed the mind of Rokitanski. He says:-"The products of typhous bloodstasis deposited in intestinal typhus in the follicular apparatus of the bowel, in broncho-typhus in the bronchial glands, and probably in plague typhus in different superficial lymphatic glands, appear to us so analogous in many points with medullary carcinoma, that we do not hesitate, in accordance with an opinion long entertained, to award it a place here." 1 And again, "The product of typhus presents in its first, but still more in its later stages of metamorphosis, the greatest analogy with cancerous growths, and more particularly with medullary cancer."

Other points of similarity will present themselves to the reader when he compares the foregoing observations on cancer with those previously made on typhoid fever. Thus, both diseases are characterized by the great diminution in the amount of pepsin.2 Again, Andral first drew attention to the deposit of pigment in the intestinal villi of those who had died

1 Rokitanski's Pathological Anatomy, vol. i. p. 282. Sydenham Society's Translation.

See pp. 121 and 278.

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of fever, and we have seen how frequently the same condition is remarked in those who have been affected with cancer. Furthermore, in these diseases only have I met with crystalline deposits in the villi; and although I am led to believe, from their microscopic characters, that these were different in their chemical composition, yet their occurrence is a matter of interest.1

I do not wish, by pointing out these analogies, to insinuate that cancer and fever originate from the same morbid material; I merely desire to show that in each the disease is of a general character, and that if we suppose the one to arise from a poison in the blood, we can scarcely refuse to admit the possibility of the same occurrence in the other.

One of the most remarkable characters possessed by cancers is their power of independent growth. A small tumour may form in some fleshy part, and increase so rapidly that the whole nutrition of the body seems to be concentrated in it, and the other structures lose their bulk in proportion to the rapidity of its enlargement. May not the following experiment afford us some hint as to this mysterious power? A portion of a large and quicklygrowing "recurrent tumour" of the breast was boiled in acetic acid. With the exception of a few fibres it quickly dissolved. The fluid was filtered and evaporated to dryness; and it was then mixed with distilled water and boiled, so as to separate the albuThe fluid was again filtered and evaporated on a water-bath, and the residue was placed beneath a bell glass, with a capsule containing sulphuric acid.

men.

1 See p. 120.

It formed a brown coloured mass, whose attraction for water was so intense that it became damp if taken from beneath the glass even for a few moments. It retained this power for many months, but at last its appearance changed, and it was converted into a dry, chalky mass.

The hygroscopic property of many animal substances is well known; but I am not aware that any attempt has been made to show what influence this may have upon growth and secretion. It can be readily imagined that if, in disease, any cellular structure should separate a material having an unusual attraction for fluid, an afflux of blood towards it would take place, and rapid and unusual growth would be excited. It is, I think, probable that other pathological phenomena may admit of an explanation on physical principles. If in the growth of ovarian cysts, a fluid is secreted having a greater density than the blood, or possessing a great attrac tion for water, exosmosis from the vessels will take place, and the contents of the cyst be in this way augmented.

In inquiries of this kind we approach a subject of the utmost difficulty, viz., the relation and subordination of chemical and physical forces to the phenomena of life, and their relations, moreover, to the phenomena which we term degeneration, disease, and death.

The life of every tissue in the healthy human being not only includes a growth bounded by natural limits, but the growth must be so interstitial and progressive that it shall exactly conform to the laws which regulate the normal development of each part of our