434 MR. A. J. EWART ON ASSIMILATORY INHIBITION. 
further information is given concerning the persistence of the 
power of movement in this form. 
Actual observation shows that the movement of Bacterium 
Termo remains quite active in 1-per-cent. KNO,, 10-per-cent. 
cane-sugar, or 5-per-cent. grape-sugar; in 24-per-cent. KNO,, 
20-per-cent. cane-sugar, and 10-per-cent. grape-sugar, fewer 
Bacteria move and the movement is slower; in 3-per-cent. 
KNO,, 25-per-cent. cane and 15-per-cent. grape sugar, a few 
Bacteria still show distinct but slow translatory movement, but 
only a very slight attraction to air-bubbles ; in 5-per-cent. KNO,, 
30-per-cent. cane-sugar and 20-per-cent. grape-sugar, all trans- 
latory movement ceases. If the Bacteria have been kept in 
ordinary sterilized tap-water for 2-3 hours, they show almost 
undiminished activity of movement, but now in a 20-per-cent. 
solution of cane-sugar, instead of a 30-per-cent. solution as with 
Bacteria fresh from Agar-tube cultures, all movement at once 
ceases. If sterilized solutions of cane and grape sugar, 10-per- 
cent., 20-per-cent., 30-per-cent., and 40-per-cent., are inoculated 
with B. Termo, either the cultures do not develop, or, if they do, 
ihe Bacteria are all immotile forms and show no movement even 
when the solutions are diluted down to 5 per cent. Hence, though 
the ability of the Bacterium to retain its power of movement in 
strong solutions of sugar is weakened when kept for a few hours 
in water, the converse does not hold, for cultures made in strong 
sugar solutions show no power of movement at all. 
It is possible, however, to conduct accurate direct observations 
by the Bacterium method upon the absence or persistence of 
assimilation in solutions of 10-per-cent. to 15-per-cent. grape- 
sugar or in 20-per-cent. grape-sugar. 
Experiments with Elodea, Utricularia, Bryum, Funaria, and 
Allium show that in solutions of these strengths the power of 
assimilation remains fairly active as long as the cells are living, 
though in Elodea the cells may be completely plasmolysed, the 
plasmolysis being less marked in Bryum and Funaria, still less 
in Allium, and not at all in Utricularia. Assimilation is natu- 
rally not so active in a 20-per-cent. solution of cane-sugar as it is 
normally, but the weakening is probably simply due to physical 
causes, viz. the withdrawal of water and the lessened exposure of 
the chlorophyll grains in the plasmolysed condition. It does not 
follow that because cells are immersed in a strong sugar solution 
that therefore the cell-sap will contain a similar percentage of 
sugar and thereby cause, if sufficiently concentrated, a stoppage 
