the Jerusalem Artichoke ( Helianthus tuber osus). 225 
as in so many other cases, to an unorganised ferment ? Sachs 
concludes that this is the case, and that the ferment resembles 
invertin. He does not, however, quote any experiments on 
the point. 
The material used for the investigation was the tubers of the 
Jerusalem artichoke (. Helianthus tuber osus). Examination of 
the young shoots and roots arising from the germinating tuber 
showed that, while inulin was present in them, there was a far 
larger proportion of sugar there also than was present in the 
tissue of the resting artichoke. Inulin, as has been mentioned 
above, is known to be capable of conversion into sugar, and there- 
fore the abundance of the sugar in these parts suggests that it 
has arisen at the expense of the inulin, and that consequently 
in the germinating tuber something may be looked for capable 
of converting the one into the other. The sap of the tuber 
when expressed was nearly neutral ; with very sensitive litmus 
paper a trace of acidity could be detected, but so little as to 
negative the idea that the conversion was brought about by 
the instrumentality of an acid. The probability of the con- 
version being due to a ferment-action was at once apparent. 
Tubers of the artichoke were planted and allowed to ger- 
minate till the young plants arising from them had attained a 
height of about six inches above ground. The tissue of the 
tubers was now found to have become much altered, the in- 
terior having become spongy and the cells almost empty, while 
on the outside and for some distance inwards it was firm and 
succulent. Microscopic examination showed the cells of this 
outer part to be filled with colourless cell-sap, from which by 
appropriate treatment the well-known sphaero-crystals of 
inulin could be separated out. There was a considerable 
quantity of sugar present, but no starch, neither extract nor 
sections giving any reaction with iodine. The tubers were 
minced finely and extracted with glycerine, in which inulin is 
insoluble. After twenty-four hours the glycerine was strained 
off and the extract dialysed till the dialysate failed to reduce 
Fehling’s solution. 
The subsequent experiments with such a glycerine extract 
