430 MR. A. J. EWART ON ASSIMILATORY INHIBITION. 
Rubus After 10 days the leaves show distinct but weak evolution 
odoratus. of O, and contain abundance of starch. If then kept 
for 2-3 days in darkness at 30° C., a distinct diminution 
of the starch and a moderately active evolution of O 
are shown. After 15 days the leaves are yellowish in 
parts, but even the normal green parts show no evolu- 
tion of O, and the starch is very abundant. If kept in 
darkness for 3 days at 30? C., all the leaves which re- 
main normal and living show a fairly active evolution 
of O anda marked diminution of the amount of starch 
present. 
Vitis vinifera | After 10 days a weak evolution of O is still shown, but in 
and Vitis parts none. After 12 days no evolution of O, the cells 
Labrusca., are loaded with starch, but the chlorophyll grains are 
otherwise normal. After 3 days in darkness at 30° O., 
a fairly active evolution of O is shown in all cases and 
the starch is distinctly diminished in amount. 
4Esculus Hippo-| After 7 days evolution of O is quite weak. After 10 days 
castaneum. the mesophyll at bases of leaflets in parts turns yellow, 
rest of leaf green and normal, but no evolution of O. 
In darkness for 3 days at 30° C., the greater part of 
the leaf remains green and shows a moderately active 
evolution of O, the starch being distinctly reduced in 
quantity. 
It is not always possible to secure a return of assimilation by 
keeping the plants in darkness and allowing the respiratory 
activity of the leaf-tissues to use up a certain amount of the 
accumulated carbohydrate, and permit a resumption of assimila- 
tion, for the leaf may have been so injuriously affected by the 
treatment to which it has been subjected, that it may die when 
kept in darkness without any appreciable amount of carbohydrate 
being removed or any return of assimilation taking place. 
In an atmosphere containing a large, but not too Jarge, per- 
centage of CO,, since assimilation goes on more actively, it is 
natural to expect that in the isolated leaf the maximal accumu- 
lation of carbohydrates and consequent stoppage of assimilation 
will take place with much greater rapidity than in ordinary air. 
Thus adult leaves of Vitis vinifera and V. Labrusca were exposed 
as previously, but in a bell-jar in an atmosphere containing 10 
per cent. of CO,, renewed daily, the plants being shielded from 
too intense sunlight, and the temperature within the bell-jar 
never being allowed to rise above 30? C. At the end of 3 days 
the leaves still show in parts a weak evolution of oxygen, but 
in parts none. After 4 days the leaves are quite green and 
normal, but the cells are loaded with starch and no evolution of 
