860 CONCLUDING REMARKS Cuar. XV. 
power was transferred to the basal parts of the hairs, 
or that the surface of the leaf has been prolonged 
upwards at numerous points, so as to unite with the 
hairs, thus forming the bases of the inner tentacles. 
The above named three genera, namely Droso- 
phyllum, Roridula, and Byblis, which appear to have 
retained a primordial condition, still bear glandular 
hairs on both surfaces of their leaves; but those on 
the lower surface have since disappeared in the more 
highly developed genera, with the partial exception 
of one species, Drosera binata. The small sessile 
glands have also disappeared in some of the genera, 
being replaced in Roridula by hairs, and in most 
species of Drosera by absorbent papille. Drosera 
binata, with its linear and bifurcating leaves, is in 
an intermediate condition. It still bears some sessile 
glands on both surfaces of the leaves, and on the lower 
surface a few irregularly placed tentacles, which are 
incapable of movement. A further slight change 
would convert the linear leaves of this latter species 
into the oblong leaves of Drosera anglica, and these 
might easily pass into orbicular ones with footstalks, 
like those of Drosera rotundifolia. The footstalks of this 
latter species bear multicellular hairs, which we have 
good reason to believe represent aborted tentacles. 
The parent form of Dionza and Aldrovanda seems to 
have been closely allied to Drosera, and to have had 
rounded leaves, supported on distinct footstalks, and 
furnished with tentacles all round the circumference, 
with other tentacles and sessile glands on the upper 
surface. I think so because the marginal spikes of 
Dionza apparently represent the extreme marginal 
tentacles of Drosera, the six (sometimes eight) sensitive 
filaments on the upper surface, as well as the more 
numerous ones in Aldrovanda, representing the central 
