Dr. A. B. Frank: see his remarkable 'Beiträge 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. The solution was allowed to evaporate, until it became so thick
that it set hard in two or three seconds, and it never injured the tissues,
even the tips of tender radicles, to which it was applied. To the end of
the glass filament an excessively minute bead of black sealing-wax was
cemented, below or behind which a bit of card with a black dot was fixed to
a stick driven into the ground. The weight of the filament was so slight
that even small leaves were not perceptibly pressed down. another method of
observation, when much magnification of the movement was not required, will
presently be described. The bead and the dot on the card were viewed
through the horizontal or vertical glass-plate (according to the position
of the object), and when one exactly covered the other, a dot was made on
the glass-plate with a sharply pointed stick dipped in thick Indian-ink.
Other dots were made at short intervals of time and these were afterwards
joined by straight lines. The figures thus traced were therefore angular;