THE CANCER PROBLEM 109
They are transitional forms. (The mixed tumours of Wilms are not all malignant, some being merely embryomata.)
3. Trophoblastomata (malignant neoplasms).—Pathological manifestations of the asexual portion (trophoblast) of the life-cycle and sometimes—whether or not always is not at present known—attempting to repeat the germ-cell portion of the life-cycle, as shown by the researches of Farmer, Moore, and Walker. They are not known to differentiate actual functional gametes, eggs or sperms. They never include or repeat any part of an embryo. They are never composed of somatic (“ embryonic “) cells, though they may mimic such or even resemble no other cells in the body. As Sir James Paget pointed out long ago,* they are “imitation tissues.” They exhibit powers of unlimited growth and increase, and they nourish themselves by eroding and destroying normal cells and tissues in a manner exactly like that of the trophoblast of normal development.
To illustrate the points to be considered, I have put out
* The designation of a malignant neoplasm as an “imitation tissue “ was first used by the writer about a year ago (1903) in an address to the Edinburgh Pathological Club. The clear recognition of the existence of such “imitation tissues,” as well as of the close resemblance, amounting to identity, of benign tumours to normal tissues, will, however, be found in Sir James Paget’s classic work, “Lectures on Surgical Pathology,” 1870, third edition, pp. 382 and 387. This book is a veritable treasure-house of valuable information. History does indeed repeat itself, and, according to Virchow, in 1815 Fleischmann explained that the tumours were “only copies of normal organic parts of the very same body in which they arise and subsist.” The authority of J. F. Meckel, according to Virchow, prevented the acceptance of this most important conclusion; indeed, this anathema has persisted or been renewed since that time, for to-day (1905) the conclusion, rightly drawn by Fleischmann ninety (!) years ago, is not accepted, so far as I am aware, by any living pathologist. Eppur si muove!