84 THE ENZYME TREATMENT OF CANCER
In the comparative account of the tumours
I shall follow the lines laid down by Wilms, and, therefore, it is his summary
of them, not mine. His account of their comparative anatomy appears to me to be
logical and convincing; and in giving his results in tabular form I should like
to say with what intense interest and instruction I have studied his writings.
As elsewhere stated, the highest and most complicated tumours—the cystic
embryomata of ovary and testis (Wilms)—are at the basis instances of identical
twins with one abnormal embryo, the embryoma. If nothing else would account for
their pathological development, the circumstance that neither they nor any of
the less complicated tumours can, from their mode of origin, contain sexual
organs might suffice. They are, therefore, sterile embryos; and in other
directions my researches have convinced me that embryonic sterility may be the
source of pathological changes.
From
the facts established concerning the tumours by pathologists, it is clear to
the comparative anatomist and embryologist that in certain respects they
present certain analogies to instances of parasitism among animals. They
differ, however, markedly in being, from the mode of their development, sterile
organisms, even in the best-developed cases. The resemblances between tumours
and parasitic Metazoa or higher animals may be exemplified by a short account
of certain snails parasitic upon Echinoderms (starfish and the like). The
series is derivable from free-living Eulima species. It may be taken as
beginning with Mucronalia eburnea, which is an external parasite, and
possesses the full organization of a snail. Stylifer linckiae is also an
ecto-parasite, but it is partially encapsulated upon the host. In this case the
foot is rudimentary, and the radula is absent.