Cuap. IL TROPAOLUM. 65 
afterwards much more so. It was nearly straight again 
in 8 hrs. 
Tropxolum tuberosum.—On a plant nine inches in 
height, the internodes did not move at all; but on 
an older plant they moved irregularly and made 
small imperfect ovals. These movements could be 
detected only by being traced on a bell-glass placed ° 
over the plant. Sometimes the shoots stood still for 
hours; during some days they moved only in one 
direction in a crooked line; on other days they made 
small irregular spires or circles, one being completed 
in about 4 hrs. The extreme points reached by the 
apex of the shoot were only about one or one and a half 
inches asunder; yet this slight movement brought the 
petioles into contact with some closely surrounding 
twigs, which were then clasped. With the lessened power 
of spontaneously revolving, compared with that of the 
previous species, the sensitiveness of the petioles is 
also diminished. These, when rubbed a few times, 
did not become curved until half an hour had elapsed ; 
the curvature increased during the next two hours, 
and then very slowly decreased; so that they some- 
times required 24 hrs. to become straight again. 
Extremely young leaves have active petioles; one 
with the lamina only -15 of an inch in diameter, that 
is, about a twentieth of the full size, firmly clasped 
a thin twig. But leaves grown to a quarter of their 
full size can likewise act. 
Tropxolum minus (?).—The internodes of a variety 
named “dwarf crimson Nasturtium” did not revolve, 
4 
