282 
Notes. 
products, such as cane-sugar, and begin to draw their supplies from 
the more permanent starch. To enable the cells to do this effectually, 
the somewhat starved protoplasm now commences to elaborate the 
needed diastase more rapidly, and the secretion of the enzyme 
becomes accelerated as the starvation-point of the cell is reached. 
According to this view the secretion of diastase by the leaf-cell is, 
like that of the embryo of the Grasses, to some extent a starvation- 
phenomenon. 
We have been able to bring forward a considerable amount of 
experimental evidence in favour of this view. 
We know, from the experiments of Boehm 1 , and of Arthur Meyer 2 , 
experiments which we have ourselves frequently verified, that the 
assimilating cells of leaves can form starch in their chloroplasts, even 
in the absence of light, providing the leaf is artificially supplied with 
a sufficiency of soluble carbohydrates, such as cane-sugar. The sugar 
thus artificially supplied is metabolized by the cell in exactly the same 
manner as if it were a direct product of assimilation. 
Now we find, if leaves are in one case supplied artificially with 
a sugar-solution, and in the other case are allowed to deplete in water, 
that in a very short time the starved leaves, the cells of which are going 
through a process of autophagy, contain very much more diastase than 
do those which have been carrying on their metabolic processes, and 
in fact storing up starch, at the expense of the sugars supplied. 
These results all tend to show that the 4 starvation-hypothesis ’ is 
probably correct as regards foliage-leaves as well as germinating seeds, 
and that the periodic fluctuations of diastase which we know take place 
in plants are indirectly connected with the amount of nutriment supplied 
to the leaf- cells by the assimilatory processes. 
The production of diastase in the leaf, like that of starch, is con- 
nected with the action of light, but it is manifest that the conditions 
which favour the production of starch are just those which inhibit, or 
tend to inhibit, the production of diastase, and vice versa. 
We have examined very carefully into Wortmann’s statement that 
leaf-diastase, when it does occur in the plant, cannot act upon the 
solid starch-granule. This statement is certainly not strictly correct, 
and we have given in our paper ample proof of this. Some starches, 
1 Bot. Zeitung, 1883, Nos. 33. 49. 
2 Bot. Zeitung, 1886, Nos. 5-S. 
