MR. A. J. EWART ON ASSIMILATORY INHIBITION. 483 
With most water-plants it is difficult to cause the maximal 
accumulation of carbohydrates to take place, but if plants of 
Elodea canadensis and Utricularia vulgaris are kept exposed to 
bright light in a frequently renewed 5-per-cent. solution of 
grape-sugar, in many of the older leaves or branchlets a marked 
accumulation of starch takes place and the power of assimilation 
is correspondingly weakened, in some cases none being perceptible. 
If moss-plants (Dicranum scoparium, Bryum cespititium) are 
kept partly immersed in a 5-per-cent. solution of grape-sugar, 
and exposed to bright light, a maximal accumulation of carbo- 
hydrates and a consequent cessation of assimilation until the 
amount is reduced, is readily produced in the older adult leaves. 
Since Saposchnikoff has shown that in isolated leaves of Vitis, 
when the further formation of carbohydrates ceases, the amount 
of sugar present in the cell-sap may reach in strength that of a 
10-per-cent. solution, it might be expected that mere immersal 
in such a solution of sugar would cause a stoppage of assimila- 
tion. Klebs * has, however, shown that various Algæ and even 
Mosses (Funaria) cultivated in 20-per-cent. cane-sugar or 10- 
per-cent. glucose may, though plasmolysed, form a new cell-wall 
and starch grains, but his experiments are not conclusive as to 
whether the plants actually assimilated or merely converted 
absorbed sugar into starch. To settle this point, direct observa- 
tions by the Bacterium method were necessary. As regards the 
movement of the test Bacteria in strong solutions of sugar, &c., 
Fischer + has shown that Spirillum shows in l-per-cent. KNO, 
or 5-per-cent. cane-sugar weak plasmolysis in a few cases, in 2- 
per-cent. KNO, or 10-per-cent. cane-sugar strong plasmolysis 
in nearly all cases, and very strong plasmolysis in 5-per-cent. 
KNO, or 30-per-cent. cane-sugar, whilst in water the Bacterial 
protoplasm re-expands and the Bacteria become homogeneous 
again. The movement of the Bacteria ceases only when they 
are strongly plasmolysed. Beyond stating that Bacterium Termo 
(Bactrillum Pseudotermo) is strongly plasmolysed by a 23-per- 
cent. solution of KNO,, and that in almost any nourishing solu- 
tion it retains the power of movement, even in a very weak acid 
culture in which other Bacteria lose the power of movement, no 
* G. Klebs, “ Beiträge zur Physiologie der Pflanzenzellen,” in Tübingen, 
Bot. Untersuch. Bd. ii. Hft. 3, 1888, pp. 500-537. E 
t Alfred Fischer, “ Untersuchungen über Bakterien," in Pringsh. Jahrb. 
Bd. xxvii. 1895, pp. 9, 31. 
