110 THE
ENZYME TREATMENT OF CANCER
certain
microscopical preparations of transient ganglion cells, parts of the asexual
generation of a dogfish. These may be taken to typify the trophoblast of a
mammal or the cells of a malignant tumour. The preparations show:
(a) cells in full functional activity prior to the
critical period, and (b) cells which, with the passing of the critical
phase, have entered upon their long, slow course of degeneration by simple
atrophy. It would have been preferable to exhibit preparations of trophoblast,
but those made after this method some years ago are now faded. The facts in the
two cases, the mammal (sheep, pig, and others) and the fish (Scyllium, Raja,
and others), are, however, quite similar. There is, indeed, only one mode
of development in vertebrate animals. Freshly made preparations of human
trophoblast of, say, the fifth and ninth weeks of gestation would display the
like bloom on the one side of the critical period and the same decay on the
other. Such figures of mammalian trophoblast have, indeed, been published
already in the writings of my friend Dr. J. P. Hill.
The
question which I wish to discuss is one which interested me exceedingly some
years ago, long before its significant hearings upon the cancer problem were
obvious. In a nutshell it is this: Why do these and certain other cells of a
fish development, like those of the mammalian trophoblast, go on flourishing
for a certain definite portion of the early development, whilst the parts of
the sexual generation, “the embryo,” are unfolding, and then with an almost
tragic suddenness commence to degenerate and die? What brings this remarkable
change to pass, one which in human development is lacking, if “the embryo” be
absent or very abnormal?
Cancer
is an irresponsible trophoblast. The unfolding