THE PARASITE OF CANCER.

Dominion, Volume 5, Issue 1326, 2 January 1912, Page 3

THE PARASITE OF CANCER.

LECTURE BY SIR HENRY BUTLIN. At the Royal College of Surgeons recently, Sir Henry T. Butlin was to have delivered tho first of his two lectures on ihe Parasite of Cancer," but, because ot loss of voice, was unable to do so. Dr. Horace Para more read the lecture, in winch Sir Henry maintained that (lie cancer cell is a new creation, an independent organism, which lives as a parasite in tho body of the animal which is suffering from cancer. It most, rloselv rescmbles the protozoa—the lust or lowest class of auimals. In his paper Sir Henry Bullin considered that there ii no essential difference between cancer cells and certain oilier parasites in the relation to their host, and that almost all the phenomena of cancer can be explained on this theorv. luo parasites of which ho spoke were the protozoa, and ho used the protozoa, not because he intended to insist that the cancer cells must be included amongst tno protozoa, but because they most closolv resemble tho protozoa, in their relation to tho body of the host, and perhaps in their mutual relations. Certain of tho protozoa appear only to live as parasites, while others of them arc never parasitic, and others, again, arc ablo to exist either as parasites or external to the bortv of anv host. Of liability of animals of the sani" species to. a. particular parasite, the evidence goes to prove that some individuals ot a species are immune to the attack of a parasite; other individuals recover from the attack of parasite, whilo other individuals again suffer badlv from if, or die. As on example the lecturer quoted nanmoglobmuria of cattle—Texas fever— which is attributed to a parasite which is not directly transferred from cow to cow, but.is introduced into the cattle bv n beetle. Whole herds are attacked in the plains of Texas. But all the animals do. not show symptoms of the disease and some of those whicli are attacked recover He gave an account of a herd of a thousand adult cattlo and 450 calves. Of the adults G3O died—an euor.-nous mortality— but only :0 of the 450.calves perished" of the disease. Calves, if Hiey suffer at all, suffer mildly. There is generally no had moelpbmuria, and at tho end of a fortnight _ they are often quite, recovered. Nevertheless the parasite mav still be found in Hie blood of these" recovered calves, so that they appear to have acquired immunity against the poison of the parasite. Whether they can be artificiallyimmunised h.v. tho injection of the blood of beasts which have been cured of the disease has not yet beeu clearly ascertained. J Parasites and Their Host. Many parasites perish with their host, tor even it they escape from the dead body ot the host they may be unable to exist outside the body of a host. But they often exhibit a marked tenacity of i l * S ey , may liTe for da ys after tho death or the host and of every tissue and cell of the host. With regard to the liability of parasitic protozoa to death, it is held by Weismaun and his school Wat the protozoa are immortal, in the sense that tho young animals are in part composed of tho substance of the parent. As a matter of fact, they undergo dcen' eratioii,-are liable to disease, fade, waste, and die, like o'tber living creatures; and they are oiten killed by the invasion of their bodies by micro-organisms—the bacteria—which are then parasites of parasites. It appears probable that (he body oi the host contains, or may produce on demand, a substance dangerous ??..,.., ol ' the Parasite which is'in it. Ot this the parasite may die. But if it can withstand the dangerous substance, it seems to gaiu greater strcugth. It has acquired immunity by its successful resistance to tho dangerous substance and may flourish more actively than before. But the activity of a parasite is probably not always the same. For, as they show alternate periods of activity and depression in cultures, eating more, growing faster, multiplying abundantly at one lime, and displaying sluggard qualities at another, so it is probable they are subject to similar periods of activily and depression in the body of,the host. The effect of parasites on their hosts depends largely on whether they produce toxins dangerous to the host or not. Many of them (such as tho parasite of malaria) "aro toxic. And these are naturally much more dangerous to the host than the nontoxic; parasites. But their virulence varies, like their vital activity; they are seldom or never so actively virulent as tho bacteria and bacilli, and take much longer to produce serious or fatal illness in the host. Whatever office the parasite may serve '—whatever effect it may produce on the host—it, for its own part, has only two objects in view, if such an expression is permitted of so lowly a creature It strives to live, and to maintan tho individual and to continue the species. If, in a suitable host, it does not succeed in reaching a suitable part of the body within a reasonable period, it will die, and the species will ceaso to exist in that host. The rapidity and completeness of its destruction will depend on many circumstances, but the general statement is correct. Moreover, the parasite breeds true. The young animals are always of the same species as the animals from which they were derived. Cancer Cells and Parasitic Protozoa. The lecturer quoted examples to illustrate the life-history of some of the resemblances of tho cancer cells to the parasitic protozoa. Some showed that they are as careful in the selection of locality as are tho varieties of parasitic protozoa. They spread in tho interstices of the tissues in which they first appear, as do certain of tho protozoa. They are conveyed in the blood and lymph, as the parasitic protozoa are. They aro deposited iu distant, tissues and oreans. like the parasitic protozoa, and they show just tho samo predilection for certain tissues and organs as do tho protozoa. They are like many of the parasitic protozoa in the fact that they live almost entirely by. osmosis. Like the protozoa, they sometimes, live for long periods of time in the body of the host without any sign of their presence, and perhaps in a state of lethargy until their vigour and activity are restored to them by somo lowering of the resistance of tho host, or by.some change in the part in whicli they have been lying, which renders it more suitable to their necessities. They do not appear to furnish toxins which are dangerous to "the health of the host, so that their effects are produced by mechanical causes—destruction of the tissues in which they live and multiply, the stoppage of blood a&d.lymphatic vessels, ■ and the changes consequent on this steppage. Theso conditions are naturally more dangerous when they affect tho vital parts. On the other hand, when, like the protozoa, tho cancer- cells are attacked by pathogenic organisms, bacteria and bacilli (as is almost invariably tho case when they becomo exposed), they are rapidly destroyed, sometimes in great masses, and the effect upon tho host is disastrous. Characteristics of Cancer Cells, Some cancer cells can live for a iraj long time ontsido (he body of the h<ist, although they do not, so fax as we know, belong to the class of organisms which are sometimes parasitic, sometimes not parasitic. Ho was not aware of any investigations to discover the longest period during which cancer cells can exist outside the body .of the host. Wo want further information on this point. But it is certain that they can live for weeks in glass tubes and then be implanted as if they were but just taken fTom the mass in which they lived. At present the cancer cells can only bo implanted with success in animals of the samo species as the animal from which they were taken. Cancer cells, like the parasitic protozoa, aro nover transformed into tissues of tho host, and the structures which they cause to bo built up are for their own service, not for the service of tho host. They are not themselves transformed into any other kind of tissuo, nor do they transform tho cells of the body into cancer cells. From tho moment they aro first unmistakably cancer cells, they remain cancel cells, and from that moment they pursuo only those two objects which aro pursued by the protozoa—to live and to reproduce. And if they fail in these objects, both tho individual and the species perish. Of this ample evidence has been furnished in theso last years, particularly by the Imperial Cancer Research for animals and by Sir Alfred Vearco Would for man. In reproduction they breed as true as any protozoan. Not only do carcinoma cells reproduce carcinoma cells, but it is invariably tho. samo variety of cell which i.« reproduced, with the smuc properties and £Q»sns ami cMwtaistics,

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