HooKER: MOVEMENT IN DROSERA ROTUNDIFOLIA 391 
tacle by way of the gland at the apex and the broken end at the 
base where the tentacle was formerly attached to the leaf blade. 
In many cases it was found necessary to puncture the cuticle in 
several places with a needle, or else to cut the pedicel into segments 
with a razor, in order to give the solutions access to all the cells of 
the tentacles. 
1. Straight tentacles—Examination of over thirty normal 
-marginal tentacles with potassium nitrate and of twenty with 
glucose solutions showed the cells of the apical half of the pedicel . 
to have a higher osmotic concentration than the cells of the basal 
half. The latter ranged from eight to nine atmospheres; the 
former from nine to eleven. In a few instances the cells on the 
dorsal and ventral surfaces of the basal portion of the pedicel 
had a higher osmotic concentration than the cells on the flanks. 
De Vries (’86, pp. 4, 5) found that the cells of Drosera tentacles 
were plasmolyzed by a three per cent. solution of potassium nitrate, 
but not by a two per cent. solution. This is seen to hold for all 
the stalk cells excepting those at the apical end just below the 
gland. 
2. Bending tentacles.—The glands of numerous tentacles were 
stimulated by rubbing with a fine brush and after fifteen to twenty 
minutes, when the tentacles had bent through an angle of 90° to 
120°, they were removed and placed in a two per cent. potassium 
nitrate solution. This treatment did not cause the tentacles to 
‘unbend. They were then mounted in some of the same solution 
and covered witha supported cover-glass. Since the tentacles 
were curved, the different effect of the solution on the convex and 
concave sides of. the teritacle could be observed. In nearly all 
cases where the movement was rapid, the two per cent. potassium 
nitrate solution had plasmolyzed the cells in the bent region on the 
convex or abaxial side, while the cells on the concave or adaxia] 
side showed no effect. Similar results were obtained by using a 
5.4 per cent. glucose solution. Examination of fifty tentacles with 
potassium nitrate and of thirty-five with glucoseshowed the osmotic 
concentration in the abaxial cells to be from six to eight atmos- 
pheres, in the adaxial cells from eight to nine atmospheres. The 
osmotic concentration of the cells on the convex side had therefore 
diminished during bending; that of the cells on the concave side 
