ASPECTS
AND ETIOLOGY OF CARCINOMA
65
developmental
cycle. The embryologist and pathologist may ignore and neglect the plain and
palpable fact, but on no theory of direct development—a thing only existing for
the higher animals in the human imagination—can any explanation whatever of the
nature of carcinoma be advanced. This would have been recognized clearly long
ago had some embryologist taken the trouble, as the writer has done since 1888,
to trace out in full the details of the life-cycle of one of the higher animals
from egg to egg. The idea of direct development, accepted without examination
of the evidences, and the erroneous belief in the somatic (body) origin of
germ-cells, have retarded the advance of knowledge to an extent difficult to
estimate.
The
nature of the argument employed in the present writing may be summarized as
follows Granted the facts of the origin, migrations, and history of the
germ-cells of vertebrates, and assuming the course of the life-cycle to be that
previously indicated, by hypothesis cancer is derived from vagrant primary
germ-cells, which, instead of forming a more or less complete embryo or
embryoma, skip this, and give rise to an asexual generation of indefinite
unrestricted powers of growth. This is, of course, purely hypothetical, but it
becomes the true explanation by the following facts: On the one hand, as my
researches have shown, the hypothetical verirrte Keime, or “lost germs,”
of pathologists not only exist, but they are numerously represented, and by
things capable of abnormal development—the vagrant primary germ-cells. On the
other hand, the carcinomatous nature of such an abnormal growth of an asexual
generation has been demonstrated abundantly by Marchand for the instances of
the pernicious growth of the chorion,chorio-epithelioina. If such a chorion, or
trophoblast, the representative more