ASPECTS AND ETIOLOGY OF CARCINOMA 61
One
reason* is, perhaps, clear. It is that the further growth of a vagrant
germ-cell, or of its progeny, to form a cancer takes place at a much later
period than that at which its embryological development into a more or less
complete embryo should have happened. (The instances of cancer with embryomata,
noted by Wilms, do not form exceptions.) Moreover, it must not be forgotten
that we are dealing here with pathological conditions, with phenomena which in
some glaring way do not conform to the normal. Cancer is, more or less, an
attribute of later sexual life or of old age. For this reason one is inclined
to suppose that it is not immediately due to the further development of a
vagrant germ-cell itself: that this latter first of all divides many times, as
it would do if in the germinal nidus, and that it ultimately forms more or less
normal forerunners of gametes, öocytes or spermatocytes. These would he in
abnormal situations and under abnormal conditions, and, under some stimulus,
they would develop as though parthenogenetically, but abnormally, to form a
trophoblast.
At
the basis, cancer is nothing more, than the production abnormally of an asexual
generation within a sexual generation. Elsewhere analogies may be seen. In hermaphroditism
we witness the conversion of the forerunners of male eggs (in what are really
females) into sperms. In certain ferns, abnormally upon the asexual generation
or fern-plant, what the botanists term “apogamy” is met with—i.e., the
appearance of a new sporophyte upon the original one; the formation of a sexual
generation or gametophyte, and of sexual organs being skipped. It has been
urged from a botanical side that comparison between apogamy in certain ferns
and carcinoma in a mammal would not be justified, because the former was an abnormal
condition. But we are dealing with abnormalities,
* Compare p. 20, et
seq. of the Introduction.