“et 
( 649 ) 
Botany. — Prof. J. W. Morr presents the dissertation of Mr. K. 
ZIJLSTRA, Assistant at the Botanical Laboratory, Groningen, 
entitled: “Kohlenstiuretransport in Bittern’, Groningen, 1909, 
and with reference to this he communicates the following. *) 
In 1877 the speaker published the results*) of investigations, which 
proved, that the carbon dioxide, which is found in considerable 
quantity in soils containing much humus, and which is at the 
disposal of the roots, cannot lead to starch-formation in the leaves, 
when the latter are in a space, free from carbon dioxide; nor can 
this carbon dioxide appreciably accelerate starch-formation in the 
open air. 
From the experiments, which led the speaker to this result, he 
further concluded, that a leaf or a portion of a leaf cannot form 
starch in a space devoid of carbon dioxide, even when parts, organ- 
ically connected with, and bordering immediately on the portion in 
question, are placed in an atmosphere which is many times as rich 
in carbon dioxide as ordinary air. The experiment, which appeared 
to prove that starch cannot be formed even from carbon dioxide, 
which is offered to immediately adjoining parts, was the following. 
A starch-free leaf was placed between the greased edges of two 
similar crystallizing dishes in such a way, that the apex was within 
the space enclosed by the crystallizing dishes, and the base was 
outside. The lower crystallizing dish contained potassium hydroxide 
solution; over the apparatus there was placed a bell-jar, containing 
air to which about 5 percent of carbon dioxide had been added. 
After the leaf had been exposed to the light for some hours, the 
base was found to contain much starch, but in the upper portion, 
even right up to the edge of the erystallizing dish, which was 3 mm. 
thick, no starch whatever had been formed. 
From this the speaker concluded that when carbon dioxide is 
abundantly present in any given part of a leaf, this can nevertheless 
not lead to starch-formation in an immediately adjoining portion, 
when the latter is in a space free from carbon dioxide. 
This result was remarkable, for the stareh-formation in the basal 
portion proved, that the carbon dioxide, offered to the leaf had indeed 
been taken up, and the presence of many intercellular spaces in the 
des Travaux Botaniques Néerlandais. 
2) J. W. Mow. Ueber den Ursprung des Kohlenstoffs der Pflanzen. Land- 
wirthsch. Jahrb, VI. 1877, p. 327—363. 
44* 
