276 RORIDULA. (Cuar. XV. 
Concluding Remarks.—The linear leaves of Drosophyllum 
differ but slightly from those of certain species of Drosera ; 
the chief differences being, firstly, the presence of minute, 
almost sessile, glands, which, like those of Dionawa, do not. 
secrete until they are excited by the absorption of nitro- 
genous matter. But glands of this kind are present on the 
leaves of Drosera binata, and appear to be represented by the 
papille on the leaves of Drosera rotundifolia. Secondly, 
the presence of tentacles on the backs of the leaves; but we 
have seen that a few tentacles, irregularly placed and 
tending towards abortion, are retained on the backs of the 
leaves of Drosera binafa. There are greater differences in 
function between the two genera. The most important one 
is that the tentacles of Drosophyllum have no power of 
movement ; this loss being partially replaced by the drops 
of viscid secretion being readily withdrawn from the glands ; 
so that, when an insect comes into contact with a drop, it is 
able to crawl away, but soon touches other drops, and then, 
smothered by the secretion, sinks down on the sessile glands 
and dies. Another difference is, that the secretion from the 
tall glands, before they have been in any way excited, is 
strongly acid, and perhaps contains a small quantity of the 
proper ferment. Again, these glands do not secrete more 
copiously from being excited by the absorption of nitro- 
genous matter; on the contrary, they then absorb their own 
secretion with extraordinary quickness. In a short time 
they begin to secrete again. All these circumstances are 
probably connected with the fact that insects do not 
commonly adhere to the glands with which they first come 
into contact, though this does sometimes occur; and that it 
is chiefly the secretion from the sessile glands which dissolves 
animal matter out of their bodies. 
RorIDULA. 
Roridula dentata.—This plant, a native of the western 
parts of the Cape of Good Hope, was sent to me in a dried 
state from Kew. It has an almost woody stem and branches, 
and apparently grows to a height of some feet. The leaves 
are linear, with their summits much attenuated. Their 
upper and lower surfaces are concave, with a ridge in the 
middle, and both are covered with tentacles, which differ 
greatly in length; some being very long, especially those 
