110 BOTANICAL GAZETTE. 
empty of starch, measured them rapidly by laying them 
pieces of board cut to the size of one square meter, 
weighed the measured portions very rapidly. Certain prec 
morning, a quantity of the same leaves of equal area gathered : 
the evening was then compared, an! the increase in weight a 3 
the quantity of starch formed in the interval. By weighing pe 
areas, and frequently, and by paying attention to the times “ 
other circumstances, a large number of results were obtaine . 
showing that the quantities given by Weber, for instance, are 
within the mark. Of course these results are not absolute. 
nevertheless, if a large number of experiments are made, the error 
is probably small. h 
xperiments were made to show both the quantity of stan 
which disappears during the day and the quantity which is forme 
during the day. A few of the numbers may be given. 412 
Helianthus, 9.64 grms. of starch disappeared in ten hours from 
face. : 
Tn the same plant 9.14 grms. were formed in the same time 
by the same area of leaf-surface. 
In another case Helianthus was used, but the leaves were ‘ 
moved from the stem to prevent the passage back of the stare 
om the mesophyll into the stems, f 
square meter was found to produce starch at the rate 0 
1.648 grms. per hour. ‘all 
mbining his experimental results and taking note of 7 
the circumstances, Sachs concludes that 20 to 25 grms. of stare 
t day by one square meter of leaf-surface aS 
, and these numbers are not only not ex- 
cessive, but experiments show that there are plants which pro- 
hose investigated here. 
me remarkably interesting and important results follow | 
from the consideration of these experimental data, 
of assimilation (formed j 
pass into the growing organs, the better these are nourished, et¢- 
