97 
Green. — On Vegetable Ferments . 
in connection with the diastase formed there. The action of 
the epithelium on the walls as well as on the contents of the 
underlying cells suggests that it secretes a cytohydrolytic 
ferment as well as a diastatic one. 
To demonstrate the existence of this enzyme is not difficult. 
If a cold-water extract of air-dried malt be precipitated by 
excess of alcohol, the precipitate collected, dehydrated, and 
dried in vacuo, it forms a white powder which is soluble in 
water. If a solution of this be prepared and a section of a 
barley-endosperm be placed in it, the dissolution of the cell- 
walls proceeds just as in a germinating seed. Boiling the 
extract renders it inert. 
This extract will dissolve the cellulose of plants other than 
the Barley, though it is not a universal solvent for this 
material. It has been found to have no action on the cellu- 
lose of the endosperm of the Date, nor on the parenchyma 
of the Apple. It acts but slowly on the thickened cell-walls 
of the endosperm of Bromus mollis . . 
Like other enzymes, it seems to work best in a very faintly 
acid medium, formic or acetic acid being most favourable. 
Though produced in the same cells as the diastase of secre- 
tion the authors consider it to be a separate ferment. Its 
action precedes the action of the diastase and the temperature 
at which it is destroyed is lower. It becomes much injured 
by exposure to 50° C., and almost paralysed if heated for half 
an hour to 6o° C. The diastase survives heating to 70° C., not 
being perceptibly injured at that temperature. The details 
of its action are not yet known ; probably it forms some kind 
of sugar. 
The histological changes noticeable in the cells of the 
scutellum throw some light on the probable mode of secretion 
in the vegetable organism. This point will however be treated 
in more detail after examining other cases. 
A difference between the cytohydrolytic and the other 
enzymes treated of so far, may be noted here. Brown and 
Morris call attention to the fact that it is only formed as the 
food-materials in the secreting cells diminish, and that an in- 
H 
