THE
EMBRYOLOGY AND ETIOLOGY OF TUMOURS 79
with
degeneration of some of their products, they leave as the basis of a tumour a
greater or less number of cells, endowed with more or fewer potentialities. As
so derived, they are not parts of the organism, but are its sisters or
brothers, identical with it in ultimate characters,
As
indicating the amount of agreement between my conclusions and those of Wilms,
and the extent to which I have adopted his views, except in so far as these are
embryological, the following passage from his latest work (1903) may be
cited: “The groups of tumours are of equal value in their etiology; they differ
among themselves only in that the one group arises from cells of the earliest
period of development—the time of the cleavage; the other, from cells of
somewhat later time—the period of the formation of the germinal layers” (p. 270).
This I would amend as follows:” In their etiology the tumours are of equal
value, and they are the results of pathological bizarre attempts at development
on the part of aberrant primary germ-cells, originally identical in characters,
and, in fine, in all respects, with that primary germ-cell, by whose unfolding
the individual harbouring such a tumour arose. As the offspring of primary
germ-cells, they may be referred to cells of the cleavage, but not to such
appertaining to the embryo. They never arise from cells of the period of
embryo-formation (Zeit der Keimblattbildung).
The
comparison sufficiently emphasizes the divergences, and, be it added, the
existence of ovarial and testicular embryomata is decisive against their
derivation from cleavage-cells in the sense of Wilms and Bonnet for none such
appertaining to the embryo can find their way into these organs, but instead
thereof there are germ-cells, which originally go back to the cleavage. In
passing, Wilms’s denial of the possible origin of an embry-