Thanks for 2d edition of Climbing plants and for CD’s recognition of HdeV’s two essays on the subject [Climbing plants, pp. v–vi, 9 n., 22, 160]. Cause of spiral growth of tendrils.

Hopes to continue study of climbing plants next summer and to observe facts mentioned in CD’s letter.

Contraction of plant roots.

Did not wish to imply that some leaves are insensitive to light, only that he could not measure their sensitivity. Contraction of roots seems common.

Experiments to determine mechanism of tendril curvature; importance of variations in cell turgidity. Contraction in roots caused by increased turgor.

Force of turgor is true cause of movement in plants. HdeV hopes to identify the substance which increases the cell’s water-absorbing power.

Movement of tentacles of Drosera.