THE EMBRYOLOGY AND ETIOLOGY OF TUMOURS
A. THE EMBRYOLOGY OF TUMOURS.
The etiology of tumours is one of the darkest regions of pathology. This is by no means due to lack of hypotheses, rather to the absence of material basis for any of those current. It cannot fall within the scope of the work to treat of anything like all the different ideas at some time or other maintained.*
The writer’s purpose will be served best by referring only to views as to the nature of pathological growths, based in some form or other upon embryology.** One cannot read the writings of the pathologists of the last twenty-five years without being struck by the un-
* For these, and their name is legion, see Wolff, Jacob: “Die Lehre von der Krebskrankheit,” Jena, Gustav Fischer, part i., 1907, and part ii., 1911.
** To account for tumours the two views most advocated at present appear to be that of “embryonic rests” or displacements, and that of metaplasy. Under “metaplasy” pathologists understand change in the character of tissue-cells, even in later life. Both are purely hypothetical, and each of them has been described as savouring of the miraculous. From the modern embryological standpoint both of them may be said to be impossibilities. Regarding “metaplasy,” as little as a man can return to his childhood, so little can any of the cells of his body take on embryonic characters, or change their nature. If any one small part of the body can do this, why not grant the same superhuman power to the whole ?