had inscribed its own course on the plate. The movement is thus
considerably magnified; for instance, if a shoot one inch in length were
bending, and the glass-plate stood at the distance of seven inches, the
movement would be magnified eight times. It would, however, have been very
difficult to have ascertained in each case how great a length of the shoot
was bending; and this is indispensable for ascertaining the degree to which
the movement is magnified.

After dots had been made on the glass-plates by either of the above
methods, they were copied on tracing paper and joined by ruled lines, with
arrows showing the direction of the movement. The nocturnal courses are
represented by straight broken lines. the first dot is always made larger
than the others, so as to catch the eye, as may be seen in the diagrams.
The figures on the glass-plates were often drawn on too large a scale to be
reproduced on the pages of this volume, and the proportion in which they
have been reduced is always given.* Whenever it could be approximately told
how much the movement had been magnified, this is stated. We have perhaps

* We are much indebted to Mr. Cooper for the care with which he has reduced
and engraved our diagrams.

[page 8]
introduced a superfluous number of diagrams; but they take up less space
than a full description of the movements. Almost all the sketches of plants
asleep, etc., were carefully drawn for us by Mr. George Darwin.

As shoots, leaves, etc., in circumnutating bend more and more, first in one
direction and then in another, they were necessarily viewed at different
times more or less obliquely; and as the dots were made on a flat surface,
the apparent amount of movement is exaggerated according to the degree of