78 THE VEGETATIVE FUNCTIONS OF PLANTS 
from the solution, at least as fast as it was made, it would 
accumulate and thus interfere with the manufacture of 
more sugar. Some of it is removed at once, either by 
nourishing the protoplasm of the cell where it was made, 
or by being translocated to other parts of the plant. But 
some of the sugar is removed from solution by being 
FIG. 58. Cell of Pdlionia Daveauana, showing starch-grains. The 
black, crescent-shaped body on the end of each grain is the amyloplasl. 
Greatly enlarged. (Cf. Figs. 8 and 59.) 
converted into starch, a substance not soluble in water. 
Thus the accumulation of starch in a leaf or other green 
tissue indicates that photosynthesis is in progress, and 
that the resulting carbohydrate is or has been formed 
faster than translocated. The conversion of sugar to 
starch is accomplished by certain plastids in the cell 
(Figs. 8 and 58). 
