116 THE ENZYME TREATMENT OF CANCER
researches, this is evidently of an (? intracellular) acid nature, like that recorded by Hartog for the chick blastoderm, etc. Petry’s work is cited in the latest edition (1903) of Hoppe-Seyler’s “Handbuch der Chemischen Analyse” (p. 387) as proving the presence of enzymes in malignant tumours.
In this connection it would be of interest to cite some of the discussions upon “ Extrazelluläre und lntrazellulãre Verdauung’ and upon the enzymes or ferments in Verworn’s “ Allgemeine Physiologie “ (pp. 161 et seq.). In studying the history of the yolk-sac of fishes I made many observations upon this question some years ago. At times one meets with cases in the yolk sac which are more “ extracellular “ than “ intracellular.” Ultimately, indeed, the latter passes into the former. In the sequel therefore, the term “ intracellular “ will be used within brackets to indicate not so much its actual nature nowadays as its origin in past times from a real intracellular digestion occurring in the presence of yolk. In the chick or skate the yolk is contained in a yolk-sac ; in a frog, within the cells of the cleavage. None the less, the ferment is the like one.* The trophoblast of normal
* It should not be forgotten that, as Verworn remarks (op. cit*., p. 171) there exists a quite overwhelming abundance of ferments.” Hartog would seem to assume that the one discovered by him in the cleaved frogs egg and in the blastoderm of the chick, which must he common to the asexual generations of vertebrates, is the same as, for example. the enzyme of the mammalian stomach. For present purposes it is not needful to insist upon this. Here it will be maintained that this enzyme of the blastoderm, trophoblast, or malignant tumour can only act in a slightly acid medium, and that in all probability it is a much weaker one than that characteristic of the pancreas. The existence of the asexual enzyme and of the sexual one may account for the necessary existence of a gastric and an intestinal digestion. The sexual generation is of later origin in time than the asexual one, and its evolution has been bound up with that of a new digestive gland and enzyme, the pancreas, etc.