THE EMBRYOLOGY AND ETIOLOGY OF TUMOURS 87
as in them, there are, according to Wilms, all transitions down to the simplest, these latter being sarcoma (cancer, or asexual generation). (7) Mixed tumours of the breast, kidney, cervix, uterus, vagina, and parotid. These are sometimes, not often, two-layered (epidermis), and they are usually made up of tissues, which can best be described as sarcomatous (cancer, or asexual generation).
B. THE ETIOLOGY OF TUMOURS.
The foregoing really forms a continuation and extension of the section on “Dermoid Cysts and Teratomata,” in a memoir* published by me some years ago. On p. 671 it was written, “How, it may be asked, shall one limit the possible reduction of an embryoma? Where shall the line be drawn ?“ The present chapter offers an answer to that question. As the writer suspected in 1900, no line can be drawn between an embryoma and a simple tumour. In this connection, apart from the references to the writings of Wilms, it may be of interest to quote from another writer and able pathologist, L. Pick.** On p. 1193, in discussing the bearings of his finds, Pick writes: “As I have already shown elsewhere, it would be false to identify in an embryoma that which, of sorts of tissue or organs, is finally preserved with that which was originally laid down in it in the germ. We know that here occasionally only a certain kind of tissue attains development, that alongside this all other tissues wither in their development—indeed, completely vanish—or by the one-sided tumour-like growth
* Beard, J.: “The Germ Cells,” part. i., Raja batis, in Zool. Jahrb., Anal. Ableil., 1902, vol. xvi., pp. 615-702 loc. cit., p. 669.
** Pick, L.: “Zur Kenntniss der Teratome: Blasenmolenartige Wucherung in einer ‘Dermoidcyste’ des Eierstocks,” in Berliner kiln. Wochenschr., Dec. 22, 1902, pp. 1189-1193.