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William Brown. 
siderations justify the conclusion that the extract in question is a 
true representation in essentials of the active principle of the fungus 
and that therefore the effects of the fungus can be explained on the 
basis of the properties of the fungal extract. 
Behaviour of Fungal Extract to Reagents. An examination of 
the effect of various substances upon the activity of the extract was 
carried out. The main results arrived at were as follows :— 
Acids and Alkalies. The extract shows a slight acid reaction. 
When this is slowly diminished by careful addition of alkali, the 
activity of the extract diminishes, and finally becomes nil in the 
neighbourhood of the neutral point. In alkaline solution the action 
is in all cases inhibited. On restoring the extract to its original 
faintly acid condition its activity is restored. With increasing 
concentrations of acid the activity of the extract again diminishes, 
the effect of mineral acids being in this respect more marked than 
that of organic acids. Thus the maximum activity of the extract is 
shown in faintly acid solution. 
Salts. Addition of salts to the extract results in a diminution 
of activity. The specific retarding action varies with different salts, 
that of magnesium sulphate, for example, being much greater than 
that of potassium nitrate. 
Substances such as cane sugar and glucose showed a slight 
retarding effect only when present in high concentration. 
Plant Juices. In accordance with the above it was anticipated 
that plant juices would, on account of the presence in them of 
various acids, salts, etc., tend to retard the action of the extract. It 
was therefore of interest to determine how far the resistance of a 
particular tissue to the action of the extract (and of the fungus 
itself) could be correlated with the retarding action of its juice upon 
the activity of the extract. The juices of highly susceptible tissue, 
— e.g ., potato, turnip—and of highly resistent tissue, e.g., liverwort, 
were compared in this respect. It was found that the retarding 
action of the latter was of the same dimensions as, and in no respect 
more marked than that of the former. The conclusion arrived at 
therefore was that the resistent power of a particular tissue to the 
action of the fungus (and fungal extract) was not directly related 
to the chemical nature of its cell sap. 
Certain Physical Relationships of Extract. 
The results here obtained may be summarised as follows:— 
a. Relation to Heating. The activity of the extract, both as 
