Cuar. X.J SENSITIVENESS OF THE LEAVES. 189 
objects to the backs of leaves by the aid of the viscid 
secretion, he repeatedly saw the tentacles (and in one instance 
the blade) become reflexed. This movement, if a true one, 
would be most anomalous; for it implies that the tentacles 
‘receive a motor impulse from an unnatural source, and have 
the power of bending in a direction exactly the reverse of 
that which is habitual to them; this power not being of the 
least use to the plant, as insects cannot adhere to the smooth 
backs of the leaves. 
I have said that no effect was produced in the above 
cases; but this is not strictly true, for in three instances a 
little syrup was added to the bits of raw meat on the backs 
of leaves, in order to keep them damp for a time; and after 
36 hrs. there was a trace of reflexion in the tentacles of one 
leaf, and certainly in the blade of another. After twelve 
additional hours the glands began to dry, and all three leaves 
seemed much injured. Four leaves were then placed under 
a bell-glass, with their foot-stalks in water, with drops of 
syrup on their backs, but without any meat. Two of these 
leaves, after a day, had a few tentacles reflexed. The drops 
had now increased considerably in size, from having imbibed 
moisture, so as to trickle down the backs of the tentacles and 
footstalks. On the second day, one leaf had its blade much 
reflexed; on the third day the tentacles of two were much 
reflexed, as well as the blades of all four to a greater or less 
‘degree. The upper side of one leaf, instead of being, as at first, 
slightly concave, now presented a strong convexity upwards. 
Even on the fifth day the leaves did not appear dead. Now, 
as sugar does not in the least excite Drosera, we may safely 
attribute the reflexion of the blades and tentacles of the 
above leaves to exosmose from the cells which were in 
contact with the syrup, and their consequent contraction. 
When drops of syrup are placed on the leaves of plants with 
their roots still in damp earth, no inflection ensues, for the 
roots, no doubt, pump up water as quickly as it is lost by 
exosmose. But if cut-off leaves are immersed in syrup, or in 
any dense fluid, the tentacles are greatly, though irregularly, 
inflected, some of them assuming the shape of corkscrews ; 
and the leaves soon become flaccid. If they are now 
immersed in a fluid of low specific gravity, the tentacles 
re-expand. From these facts we may conclude that drops of 
.syrup placed on the backs of leaves do not act by exciting a 
motor impulse which is transmitted to the tentacles; but 
