306 A. F. W. SCHIMPER. 
is independent of light in other parts of plants so long as 
there are reserve materials to draw upon, can only be ex- 
plained by the assumption that starch can be formed in the 
chlorophyll-corpuscles of the mesophyll only by assimilation, 
and that in the other cases it has a different origin. The 
chlorophyll-corpuscles of the parenchyma of the stem and 
of the bundle-sheaths of the leaves can form starch, both by 
assimilation and by the conversion of assimilated substances 
conveyed to them from other parts. In other words, these 
chlorophyll-corpuscles combine the functions which are 
peculiar to chlorophyll-corpuscles with those which are per- 
formed by starch-forming-corpuscles. This assumption is 
further justified by the fact that the mesophyll is the prin- 
cipal seat of the assimilatory function, whilst the bundle- 
sheaths of leaves and the parenchyma of petioles and of 
stems are conducting tissues for starch; the parenchyma of 
stems is also to some extent a reservoir in which it is 
deposited.t 
It is evident that the starch, which makes its appearance 
as the first visible product of assimilation, is not directly 
formed from carbon and water, but that a number of inter- 
mediate products must be formed.” 
We may assume that the substances which are conveyed 
to the chlorophyll-corpuscles in question are nearly allied to, 
or even identical with, these intermediate products; hence 
the conversion into starch of the substances which have been 
formed in the chlorophyll-corpuscle itself, and of those which 
have been conveyed to it from other parts is really one and 
the same process. 
The results of this investigation tend to show that there 
is no such great difference between assimilating and non- 
assimilating cells, as was thought to exist. In a cell which 
contains no chlorophyll there are certain organs which pro- 
duce starch, and these organs are nothing more than im- 
perfectly developed chlorophyll-corpuscles, which may 
develope into perfect chlorophyll-corpuscles under the in- 
fluence of light. On the other hand, chlorophyll-corpuscles 
are not always merely assimilatory organs ; they perform in 
the conducting tissues and in the reservoirs of material the 
same functions as the starch-forming-corpuscles in cells 
which do not assimilate; that is, they produce starch from 
assimilated substances which are conveyed to them from 
other parts of the plant. 
1 Sachs, ‘ Exp. Phys.,’ p. 380 395 e¢ passim. 
2 Sachs, ‘Exp. Phys.’ Pringsheim has recently discovered such an in- 
termediate product, and has termed it hypochlorin (‘Monatsbericht d. 
preuss. Akademie in Berlin,’ 1879). 
