392 HooKER: MOVEMENT IN DROSERA ROTUNDIFOLIA 
had remained practically unchanged. The greatest diminution 
in the osmotic concentration of the cells on the convex side was 
observed in those tentacles that reacted most rapidly. In a few 
cases of exceptionally slow movement no diminution was observed, 
the osmotic concentration being either eight or nine atmospheres. 
The osmotic concentration of the cells in the upper half of the stalk 
was found to be the same as in the unbent tentacle. 
3. Bent tentacles.—Tentacles were stimulated by placing small 
flies on their glands, and after bending had proceeded as far as 
possible the tentacles were removed and examined. In twenty- 
five tentacles treated with potassium nitrate solutions and fifteen 
tentacles treated with glucose solutions, the cells at the base of 
the pedicel and in the bent region had an osmotic concentration 
of nine to eleven atmospheres, there being no difference between 
the two sides of the tentacle. The cells of the apical portion of 
the pedicel were found to have an osmotic concentration of ten 
to thirteen atmospheres. In a few exceptional cases the cells in 
the latter region appeared to have a higher osmotic concentration, 
but the detection of plasmolysis was particularly difficult because 
these cells were smaller than the basal cells and their contents 
were strongly aggregated. 
4. Unbending tentacles—Twenty tentacles in process of un- 
bending were examined with potassium nitrate solutions and the 
results were checked by the examination of twelve more with 
glucose solutions. The osmotic concentration of the cells in the 
basal half of the pedicel was from eight to ten atmospheres; in the 
apical half from nine to eleven. No difference was observed in 
the osmotic concentrations of the cells on the concave and convex 
sides. 
5. Unbent tentacles.—Eighteen tentacles which had become 
straight after completing a reaction were examined and found to 
be similar in osmotic concentration to the normal tentacles before 
reaction. 
The experimental data given above are summarized in the 
following table: 
Three significant facts should be noted, namely: 
1. The osmotic concentration of the pedicel cells increases 
from the base to the apex. 
