Studies on Enzyme Action. 601 
on these sugars had been tried; quite a number of yeasts are described as 
being without action on galactose. The evidence available on these two 
points was sutficient to make it very important to extend the inquiry under 
uniform conditions, to determine the action of each of the yeasts used on the 
four hexose sugars above named, as well as to ascertain the nature of the 
enzymes present in each of the yeasts. 
The points borne in mind primarily throughout the investigation were :-— 
1, Does every yeast ferment glucose, mannose and fructose equally well ? 
2. Do all yeasts ferment yalactose ? 
The experiments were begun in the Carlsberg Laboratory, at Copenhagen, 
which I visited specially for the purpose last summer; I desire to take this 
opportunity of expressing my indebtedness to Professor E. C. Hansen, both 
for the interest he displayed in the work and for the generosity with which 
the resources of his laboratory were placed at my disposal. I have also to 
thank Dr. Schionning for the manner in which he aided me to master the 
methods of cultivating and using pure yeasts so successfully elaborated in the 
Carlsberg Laboratory. 
It may fairly be claimed that the yeasts selected represent as wide a range 
of variation in morphological characters and other respects as possible; con- 
clusions based on their behaviour can, therefore, be applied in any discussion 
of the behaviour of the saccharomyces generally. 
The following is a list of the yeasts used :—* 
Saccharomyces cerevisie. Saccharomycopsis capsularcs. 
nd Carlsberg. - Klocker yeast. 
55 Thermantitonum. Saccharomyces fraguts. 
Schizosaccharomyces Pombe. Torula Kayser. 
Saccharomyces Marxianus. »  Adametz. 
% CHUGUUS. Kefir yeast. 
Saccharomycodes Ludwigit. Yeast No. 698. 
Willia anomala. Saccharomyces apiculatus. 
»  NSaturnus. A } Schweiz. 
Schizosaccharomyces octosporus. y malt Duclaws. 
A few words as to the morphological characteristics of these yeasts may 
be of interest. S. cerevisie is a typical English top-fermentation yeast, 
S. Carlsberg is a typical low-temperature bottom-fermentation yeast ; 
S. Pombe, originally obtained from Africa, exercises its maximum activity at 
36°, forming much alcohol; S. Thermantitonwm, a yeast recently described by 
* For the nomenclature adopted, compare Hansen, ‘Centralblatt fiir Bakteriologie,’ 
1904, vol. 12, p. 529. 
