556 
Green . — The supposed 
which only 150 cc. represented added water, and the remainder 
was extracted from the living Yeast-cells. 
This turbid liquid was then mixed with four grams of 
the same Kieselguhr and well shaken. On filtering it through 
paper a clear yellow liquid was obtained, having an aroma 
like that of active Yeast. 
This liquid was the material in which Buchner claimed that 
the long-sought alcohol-producing enzyme was present. It 
had a specific gravity of 1-0416 at 17 0 C. 
In its properties it closely resembled solutions of the other 
enzymes already known to physiologists. It lost its power 
of inducing fermentation on being heated, but parted with it 
at a much lower temperature than most enzymes, viz. at 
45“5°°C., its proteids being coagulated at the same temper- 
ature. The coagulum was very bulky, the extract being 
extremely rich in proteid matter. The coagulation was 
preceded by the evolution of carbon dioxide. 
When this Yeast-extract was mixed with a 37% solution 
of cane-sugar, a regular evolution of carbon dioxide com- 
menced, and proceeded with an energy which varied according 
to the temperature to which the liquid was exposed ; it 
was active even so low as o° C., but became more obvious 
at the temperature of the laboratory, and still more energetic 
at 40° C. The extract was found to work upon the same 
sugars as the Yeast itself, and to refuse to attack those on 
which the cells had no action. 
The activity noticed was not interfered with by chloroform 
or other antiseptics, nor was it abolished by filtering the 
extract under pressure through a porcelain filter. There was 
thus a strong presumption at least that no living Yeast-cells 
were present in the extract, and that whatever happened was 
due to something extracted from the cells by the enormous 
pressure employed in the process. 
In a subsequent paper ( 2 ) Buchner admits that this active 
principle is not contained in all Yeasts, the so-called ‘ German 
Yeast’ being free from it. He further states that the active 
liquid can only be preserved for a single day at the ordinary 
