HOOKER: MOVEMENT IN DROSERA ROTUNDIFOLIA 393 
Tentacles Straight Bending | Bent | Unbending Unbent 
Basal half of pedicel: 
WAP SING ae eates 8-9 6-8 9-11 8-10 8-9 
ela Side ss Ss dares ie 8-9 8-9 Q-I1 8-10 8-9 
FADICAL TIAN rare a tees 9Q-II Q-II 10-13 Q-II Q-II 
2. During rapid bending the osmotic concentration of the 
abaxial cells in the growing region decreases. 
3. When the tentacles are bent, the cells have a higher osmotic 
concentration than at any other time. 
2. RABDOIDS 
Rabdoids were first discovered by Gardiner (’85) in Drosera 
dichotoma, and he states that in Dionaea, Drosera rotundifolia and 
other species of Drosera rabdoids occur which resemble those of 
Drosera dichotoma. Gardiner described the rabdoid as a body, 
usually spindle-shaped or acicular, which occupies such a position 
that it stretches diagonally across the cell from end to end, the 
two extremities being imbedded in the cell protoplasm. They 
were present in all the epidermal cells of Drosera dichotoma leaves 
except the gland cells and the cells immediately beneath the glands. 
In the bending region of those tentacles capable of movement 
they were larger in the epidermal cells on the abaxial side than on 
the adaxial side where they were very small or apparently absent. 
When these cells lost their turgidity the rabdoids contracted and 
separated into two or more parts, but regained their spindle shape 
when turgidity was restored. A sudden blow on the cover glass 
also caused the rabdoids to assume a spherical form. 
The presence of rabdoids in the epidermal cells of Drosera 
rotundifolia leaves was confirmed. They occur in all the epidermal 
cells of the petiole, of the leaf blade and of the basal portion of the 
tentacles, including the bending region. Each cell contains a 
single rabdoid, rarely two rabdoids, situated near the outer wall 
and parallel with it. After a leaf has fed on insects, the rabdoids 
are distinctly larger than before. When plants are deprived of 
insectivorous food for any considerable period, the rabdoids 
dwindle until they are barely noticeable. Sudden shocks produced 
by tapping the cover glass or gradual pressure sustained for a 
considerable period of time cause the rabdoids to alter their shape. 
