, as the cause of the movements in question.
The term epinasty is now often used in Germany, and implies that the upper
surface of an organ grows more quickly than the
* The highly useful terms of Heliotropism and Geotropism were first used by
Dr. A. B. Frank: see his remarkable 'Beitr?ge zur Pflanzenphysiologie,'
1868.
[page 6]
lower surface, and thus causes it to bend downwards. Hyponasty is the
reverse, and implies increased growth along the lower surface, causing the
part to bend upwards.*
Methods of Observation.--The movements, sometimes very small and sometimes
considerable in extent, of the various organs observed by us, were traced
in the manner which after many trials we found to be best, and which must
be described. Plants growing in pots were protected wholly from the light,
or had light admitted from above, or on one side as the case might require,
and were covered above by a large horizontal sheet of glass, and with
another vertical sheet on one side. A glass filament, not thicker than a
horsehair, and from a quarter to three-quarters of an inch in length, was
affixed to the part to be observed by means of shellac dissolved in
alcohol.
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