the Jerusalem Artichoke ( Helianthus tuber osus). 227 
power than that of A v the latter only showing what was due 
to the sugar in the extract. The dialysates were changed and 
the dialysis continued for twenty-four hours longer, when the 
difference in favour of A was very marked, the control showing 
the presence of a mere trace of sugar. 
The same results were arrived at in other cases, the details 
of the experiments, as to the relative proportions of inulin 
and extract used, being varied in many ways. 
Coincidently with the appearance of the sugar in the dialy- 
sates, the amount of inulin in the parchment tubes underwent 
diminution. The amount of precipitate thrown down by 
alcohol from the fluid containing the unboiled extract of the 
tubers became less and less as time went on, measured quan- 
tities being taken for that purpose. Similar quantities taken 
from the controls showed no such diminution. 
These results establish the presence of a ferment in the 
germinating artichoke, by whose instrumentality inulin is 
transformed ultimately into some form of sugar. The time 
taken up in the experiments is to be accounted for possibly 
by the very small quantity of the ferment present, and its 
dilution in the process of extraction. In the artichoke it is 
probable that it only exists at any particular time in the cells 
whose contents are being changed into sugar, and as it takes 
several weeks for this conversion to be brought about in any 
tuber, there must be but little ferment to be found at any 
one moment. Some experiments bearing on this point will 
be detailed later on. 
Like so many of the digestive ferments, both animal and 
vegetable, the ferment brings about a change which is quite 
easily caused by other means. The action of acids at a boiling 
temperature has already been referred to. Besides this I found 
that prolonged exposure to dilute acids at the ordinary 
temperature, and still better at about 40°C, is capable of 
bringing about the same conversion. Alkalis on the other 
hand have no action on it. Prolonged suspension in cold 
water will also transform some inulin into sugar, though the 
energy of water is very feeble compared with that of acid. 
