THE CANCER PROBLEM 115
On
p. 587 he arrives at the important conclusion that the digestion in the frog’s
egg (prior to the appearance of an embryo) and in the blastoderm of the chick (with
the embryo removed) must be a purely intracellular acid one.* For
comparative and other reasons I now apply this conclusion to the trophoblast of
a mammal and to the cells of a malignant neoplasm. No more than those of the
trophoblast do the cells of a cancer contain yolk. None the less, in both the
digestion must be the “ ancestral “ acid “peptic “ (intracellular) one,
characteristic of the asexual generation of a vertebrate, for this has been
handed down as an unconscious memory from the time when the mammalian yolk-sac
contained food material. Recent researches, especially those of Vernon, have
revealed the presence of traces of trypsin in many organs of the body. But this
enzyme has never been, and cannot be, demonstrated in any malignant tumour. On
the contrary, the work of Petry ** on many carcinomata and sarcomata has proved
the occurrence in these of a proteolytic ferment. From the author’s account of
his
* The antithesis
between digestion in an acid and in an alkaline medium struck me, as
apparently it did my old friend and teacher, Professor M. M. Hartog. At the
present time I do not think that we have got to the bottom of this; but
undoubtedly the ferments of cancer act in an acid medium, while those of the
sexual generation, man, act best in an alkaline medium—with the exception of
pepsin; but the peptic digestion of the stomach, although important in its
action upon fibrous tissue, thus loosening such things as muscle-fibres
(flesh), can on occasion (after removal of the entire stomach by operation)
be dispensed with. For shortness and clearness, when this chapter was first
published, I spoke of “acid-ferments” and “alkaline-ferments,” meaning thereby
ferments or enzymes acting respectively in acid and alkaline media. A certain
anonymous critic might note this, and in future be mindful of the maxim, “Teach
not a parent’s mother to extract the embryo juices of the egg by suction,” etc.
** Petry, Eugen: “Em Beitrag zur Chemie
maligner Geschwülste,” Zeitschrift fur Physiologische Chemie, 1899, vol.
xxvii., p. 398.