BOTANICAL GAZETTE. 109 
generally, viz., that the starch disappears from the leaves in the 
form of glucoses, which travel by way of the vascular bundles 
into the stems, and thus pass to the places where they are used 
up in growth. 
Some very telling observations were made in this connection, 
and the dependence of the processes on temperature again show 
forth clearly. 
These results lead to the conclusion that the process of meta- 
morphosis into glucoses and translocation of the products of as- 
similation are also going on during daylight, though they are less 
evident, because more starch is then being formed and accumula- 
ted than is abstracted at the time. Moll proved that such is the 
case by exposing leaves to the sunlight, but in an atmosphere 
devoid of carbon dioxide, the starch already in the leaves disap- 
were tested and found to be nearly emptied of starch. Other ex- 
periments proved that depletion occurred in a few hours, the time 
depending on the temperature. ; 
Further experiments demonstrate that the starch travels in 
the form of glucoses in all the above cases, but it is not prove 
whether the metamorphosis is effected by forces in the chlorophyll 
grains themselves or by means of diastatic ferments in the cells 
of the leaf. : 
Perhaps the most ingenious part of the paper is that which 
now follows. It is well known that Weber’s patient and thor- 
ough researches on the energy of assimilation led to two impor-: 
tant results among others: (1),that the quantity of starch formed 
by acertain area of leaf surface in a certain time may be rela- 
tively very large, and (2) that different plants probably differ spe- 
cifically as to the quantity of starch formed in their leaves. 
question, i. e., how much starch is produced in, say one square 
meter of leaf surface by assimilation during, say ten hours of bright 
sunlight? The great difficulties in Weber’s researches were con- 
nected with the enormous labor necessary to measure the leaf sur- 
ace accurately, 
: Sachs resolved the matter in a manner which we may summa- 
‘ize thus: He cut off portions of large leaves found to be 
