272 
Notes. 
An examination of all the published facts relating to the occurrence 
of diastase in plants revealed a curious number of conflicting state- 
ments, from which it was impossible to draw any conclusion without 
further investigation. The importance of such an investigation 
from a physiological point of view was manifest, and during its 
progress we found ourselves carried by degrees into all the vexed 
questions connected with the first formation of starch in the chloro- 
plasts of the foliage-leaf, the mode of the dissolution of this starch 
and its translocation in the plant, and the nature of the metabolized 
products between the starch and the formation of new tissue. 
Although our investigation is by no means as complete as we 
could wish, we think that the results so far obtained will not prove 
devoid of interest either to the chemist or the vegetable physiologist. 
Of the previous work bearing upon the occurrence and formation 
of starch in the chlorophyll-bodies of green leaves undoubtedly the 
most important is that of Sachs, who, in a series of papers dating 
from 1862, clearly established the important fact that the appearance 
of so-called autochthonous starch in the chlorophyll-granule is induced 
by, and is dependent on, the action of light of sufficient intensity, 
and that the green colouring-matter of the chloroplast is as essential 
to the production of this starch as it is for the decomposition of 
carbon-dioxide. Sachs, in fact, for the first time clearly formulated 
the proposition that the production of starch in the chloroplast is 
directly connected with assimilation, and also showed that when plants 
are placed in the dark the starch disappears from their chloroplasts 
to re-appear again when light of a sufficient degree of intensity is once 
more allowed to fall on them. 
The immense importance of these facts was duly appreciated by 
their discoverer, who was led by them to the further recognition 
of a periodic daily change in green leaves, by which the starch, 
formed in the chloroplasts during the hours of daylight, is wholly 
or partially re-dissolved and removed from the leaf during the 
night, to supply the constant demands of growth and respiration. 
In his important paper of 1884 \ Sachs still further advanced our 
knowledge of the starch-building, and the subsequent metabolism 
of starch in the leaf. He devised an iodine-method, now well known, 
for roughly determining the relative amount of starch in the leaf, 
1 Ein Beitrag z. Kenntniss der Ernahrungsthatigkeit der Blatter. Arbeiten des 
Bot. Instituts in Wurzburg, 3. 1, 1884. 
