Alcoholic Enzyme in Yeast. 561 
The contents of this flask were then examined for alcohol, 
and found to contain ■2°/ 0 . 
B was allowed to digest for three days longer. It then 
contained the same proportion of alcohol. When boiled it 
gave hardly any coagulum, the proteids being apparently 
digested, as Buchner says they were in his experiments. 
E was examined after four more days. It contained almost 
exactly the same percentage of alcohol. 
Two days later, the control flask A was similarly examined, 
and found to contain the same amount of spirit. 
There had thus been during the whole time no additional 
amount of alcohol formed. 
From a consideration of the whole series of my experiments 
I can see no satisfactory evidence in favour of the existence 
of Buchners enzyme, at any rate in the Yeasts in use in 
English brewing. The diminution in specific gravity in the 
digesting fluid in the quoted series of experiments appeared to 
me at first to point in that direction, but had the enzyme 
been present I think I should have found this diminution more 
regular, and I should have found at least ten times the C0 2 
evolved. The amount of alcohol formed would also have 
corresponded to the weight of sugar lost. The extraction 
of the Yeast has in all my experiments led to the presence of 
a measurable quantity of alcohol in the digestions at the outset. 
The Yeast-extract which I obtained from the Tottenham 
Yeast contained * 4 °/ 0 of spirit. In no case did I find evidence 
that this initial amount of alcohol was increased. 
My own results receive confirmation from some researches 
published quite recently by Will (4), and by Lindner (5), Del- 
bruck, and others, who have also failed to extract the enzyme 
by the method detailed by Buchner. 
I do not think that Buchner’s statement that the activity 
of the enzyme is correlated with the presence of coagulable 
proteid in the Yeast-extract is correct. Certainly I found 
many extracts containing quite a considerable amount of 
coagulable proteid to be entirely without enzyme-action when 
digested with saccharine solutions. 
