114 THE
ENZYME TREATMENT OF CANCER
blastoderm
of a bird, all these being in the main homologous structures or asexual
generations. What is found to obtain in the one must hold good in the others,
for there is but one mode of vertebrate development. In this direction, when
dealing with the yolk and merocytes of fish-development and with the mammalian
trophoblast in past years, some results had already been obtained ;
and in taking up the thread anew one’s thoughts reverted naturally to the chick
blastoderm as a readily obtainable material. Then came the recollection that
the work had been done already for the chick and frog. In a recent publication
Professor M. M. Hartog* writes (p. 587) “ One thing is clear as the result of
this all probability henceforward is in favour of the view that in the animal,
as in the plant, a cell can only utilize its reserves secondarily and
mediately—by the internal secretion of an enzyme.” The author commences his
paper by commenting upon the known facts that it has been shown in every case
examined that in the utilization of reserves in plants a ferment or enzyme is
always present, which in suitable circumstances can effect in vitro the
same process—usually of hydrolysis—which the living organism performs. He next
proceeds to demonstrate that in the early development of animals, in the cells
of the frog’s egg, in which cleavage is ended, hut no embryo yet present, and
in the blastoderm of the three or four days’ chick, there is a proteolytic
ferment present. Under proper precautions, this in acidulated solution (from
0.3 to 0.7 per cent. hydrochloric acid) gives the biuret reaction
showing the presence of peptone. The reaction is absent in neutral or slightly
alkaline solution.
* Hartog, M. M.: Some
Problems of Reproduction—II.,” Quarterly Journal of Microscopical Science, 1904,
vol. xlvii., pp. 583-608.