Notes . 
28 
especially buckwheat-starch, are very readily acted on by the leaf- 
diastase of a plant like Pisum sativum , and even wheat-starch and 
barley-starch are slowly acted upon. In the case of buckwheat-starch 
it is not difficult to obtain considerable action within two hours of the 
commencement of the experiment. In fact this starch can be attacked 
by the diastase of some leaves with a rapidity approximating that 
under which the starch is observed to disappear in the living leaf- 
tissue. 
In his contention that the starch of leaves only disappears under the 
action of living protoplasm, and is not conditioned by any enzyme- 
action, Wortmann relies, not only upon the supposed rarity of diastase 
in leaves, but also upon the alleged impossibility of procuring the 
dissolution of starch in the leaf when the plants are placed in an 
atmosphere of carbon dioxide, or when the free respiration of the leaf 
cell is interfered with in any other way. 
It seemed to us however that under the conditions of Wortmann’s 
experiments little or no disappearance of starch could be expected to 
take place in the leaf, even if its dissolution depended upon the simple 
chemical function of a portion of the cell-contents. 
There seemed to be a much better chance of obtaining solution of 
starch in the leaf-tissue under the action of its own diastase if the leaf 
could be completely killed without destroying or inhibiting the action 
of the contained enzyme. The products of hydrolysis could then 
readily pass outwards when the physical conditions for diffusion were 
favourable. 
With this object in view the leaves were killed by immersion for 
some time in an atmosphere charged with chloroform vapour, and 
were then placed under the most likely conditions for dissolving the 
starch under the action of the leaf-diastase. 
Although numerous trials were made with leaves of Tropaeolum , 
Hydrocharis, and Pisum sativum , by half-leaf methods, we have never 
succeeded in satisfactorily demonstrating dissolution of starch within 
the cells of the killed leaf, not even if already partially depleted leaves 
were taken, in which the diastase was at a maximum. 
Apart entirely from any metabolic function of the cell, it is evident 
that the starch-grains embedded in the chloroplast of a living leaf-cell 
must, whilst still surrounded and carried along by the streaming 
protoplasm, be placed under conditions far more favourable to the 
action of any enzyme the cell may contain, than is the case when all 
U 
