On some resemblances of crown-gall to human cancer / Erwin F. Smith.

  • Smith, Erwin F. (Erwin Frink), 1854-1927.
Date:
[1912]
Catalogue details

Licence: In copyright

Credit: On some resemblances of crown-gall to human cancer / Erwin F. Smith. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    strands which bore their way through normal tissues of the body, sometimes for long distances, developing from certain portions of these strands secondary tumors. (2) Small groups of cancer cells are dis- lodged from the parent tumor and carried as floating islands in the blood stream or lymphatics to develop secondary tumors where they lodge. The first of these ways has been definitely established by observa- tion; the second by inference, no connect- ing strand having been discovered. Nat- urally these secondary tumors, being de- rived from the primary tumor, tend to par- take of the nature of the tissue from which the primary tumor has developed. For ex- ample, if the primary tumor be in the stomach, the secondary tumors are likely to contain glandular cells resembling those of the stomach, wherever they may be de- veloped. This is such a striking peculiarity that it is often possible for the animal pathologist to tell from the study of his sections whether the cancer is primary or secondary, and, if secondary, in what organ the primary tumor is located. In case of tumors located in an organ containing all three of the embryonic layers or developed out of cell-rests of this nature we might have in the tumors a jumbled-up mass of all sorts of tissues—skin, bone, teeth, hair, muscle, nerve, etc. This at least is one method of explaining the embryomata. Having found no parasite in the cancer cells, a majority of the animal pathologists have given up the idea that cancer can be of parasitic origin. For a generation the research workers fell back upon Cohn- heim’s hypothesis that cancers were due to the development of small fragments of tissue cut off from the parent layer during embryonal growth, to be enclosed in other tissues and lie dormant until acted on ab- normally later in life by some unknown stimulus. But while studies of the animal body show that such separation of small portions of tissue from the germinal layer is not uncommon, research workers on cancer are now generally agreed, I believe, that there are many phenomena connected with the development of cancer for which this hypothesis of Cohnheim offers a wholly inadequate explanation. Moreover, what induces these dormant cells to de- velop was never determined. A very favor- ite theory with cancer specialists has been that the cancer cell itself is the only para- site, and that no infections could be ob- tained on animals unless the living cancer cell were present. This hypothesis must now be abandoned owing to the discovery by Peyton Rous (1911) that sarcoma of chickens may be produced in the absence of cancer cells, i. e., by cancerous fluid fil- tered free from all traces of living cancer cells. So far as I know he has not expressed any opinion as to the nature of the infec- tion which has been separated from his ground chicken sarcomata by centrifuging and also by filtration through Berkefeld bougies, but in the light of the evidence we have secured from plants I believe you will agree with me that it can be nothing else than a living microorganism, minute enough to pass through the walls of the rather coarse filter. In crown-galls I have not found the sec- ond method of formation of secondary tumors, namely, by the detachment of small fragments of the primary tumor to be carried in a stream and lodged at a dis- tance. This method we should hardly ex- pect to find in plants, owing to the fact that there is no rapid blood stream such as we find in animals, neither does it seem to be more than an epiphenomenon in tumor growth, the essential thing being the ab- normal internal stimulus to cell division. The first method of propagation, namely, by strands, occurs, however, and parallels to my mind very strictly what occurs in