8 7 
Green . — On Vegetable Ferments. 
This form of diastase is absent from the resting seed and 
only makes its appearance at the onset of germination. That 
it is a true product of secretion is made probable by histo- 
logical observations upon the epithelial cells of the scutellum 
in which its formation is asserted. The authors say that 4 the 
histological changes in the columnar cells during germina- 
tion are closely paralleled by those which occur in animal 
cells while actively secreting, and in the glandular cells of 
Dionaea muscipula under like circumstances, as determined 
by Gardiner.’ 
The existence of these two forms of diastase has been 
indicated also by Lintner and Eckhardt, in a comparison 
which they have made of the diastatic power of raw and 
germinated grain. They point out further differences between 
them as to certain features of their action, particularly with 
regard to the temperatures which are most favourable to their 
respective action. The optimum temperature for malt- 
diastase is between 50 and 55 0 C., while that for barley-diastase 
is at least 5 degrees lower. The diastatic power of the latter 
variety at 40° C. is as great as that of the former at 14*5° C. 
Haberlandt 1 contends that the diastase of secretion has 
for its seat of formation also the so-called aleurone- layer of 
the barley-grain. He describes the cells of this layer as 
assuming in germination the general characteristic features 
of glandular cells, and projecting in papilla fashion into the 
interior of the endosperm. When this layer is isolated and 
grains of starch laid on it, Haberlandt says it corrodes and 
dissolves them. Brown and Morris dispute the accuracy of 
his experiments, attributing the results he obtained in such 
corrosion to the fact that the whole endosperm gradually 
becomes permeated with the ferment discharged by the scu- 
tellum, and that the cells of the aleurone-layer were conse- 
quently in contact with a solution of the diastase on their 
interior face. 
Brown and Morris call attention to the fact that secretion 
1 Ber. der deut. botanischen Gesells., 8, 40. 
