236 Green . — Germination of Jerusalem Artichoke . 
and an extract made, as in the other case. The first of these 
two extracts proved to be quite inert, while the second showed 
a power of converting inulin into sugar. The experiments 
were carried out as before in well-tested dialysers, the dialy- 
sates being examined at intervals for sugar. 
I was unable to obtain any evidence of the formation of 
ferment in the extract of the unwarmed tubers by the action 
of acid alone. I tried hydrochloric, acetic, citric, and malic 
acids, but none had any effect. This might be due to the 
destruction of the ferment by the acid as fast as it was formed, 
for it is most sensitive in this direction, as already pointed out. 
When the extract was treated with a solution of acid-albumin 
in -2 per cent. H Cl it did give rise to a certain amount of 
ferment, though less than was obtained by warming the tubers 
for twenty-four hours before the extract was made. 
The result of the investigation into the germination of the 
artichoke tuber may be briefly summarised as follows : — 
1. The stored inulin in the tuber is made available for the 
use of the plant by ferment-action. 
2. This ferment is not diastase, but a special body working 
on inulin. 
3. Its action is to produce from the inulin a sugar and 
an intermediate or collateral product. 
4. The latter differs from inulin in its solubility in water and 
alcohol, its crystalline form, and its power of dialysis. 
5. The ferment does not exist as such prior to the com- 
mencement of germination, but is present in the resting tuber 
in the form of a zymogen, from which it can be developed by 
the action of warmth, or, under certain conditions, by that 
of acid. 
6 . Its activity is only manifested in a neutral or very faintly 
acid medium, and it is destroyed by prolonged contact with 
acids or alkalis. 
