284 CONCLUDING REMARKS. Cuar. XI 
moved towards the middle of the lower surface, for there are 
no viscid. glands there by which insects can be caught. 
Although they have no power of movement, they are probably 
of some use by absorbing animal matter from any minute insect 
which may be caught by them, and by absorbing ammonia from 
the rain-water. But their varying presence and size, and their 
irregular position, indicate that they are not of much service, 
and that they are tending towards abortion. In a future chap- 
ter we shall see that Drosophyllum, with its elongated leaves, 
probably represents the condition of an early progenitor of the 
genus Drosera; and none of the tentacles of Drosophyllum, neither 
those on the upper nor lower surface of the leaves, are capable of 
movement when excited, though they capture numerous insects, 
which serve as nutriment. Therefore it seems that Drosera 
binata has retained remnants of certain ancestral characters— 
namely a few motionless tentacles on the backs of the leaves, 
and fairly well developed sessile glands—which have been lost by 
most or all of the other species of the genus, 
Concluding Remarks.—F rom what we have now secn, 
there can be little doubt that most or probably all the 
species of Drosera are adapted for catching insects by 
nearly the same means. Besides the two Australian 
species above described, it is said* that two other 
species from this country, namely Drosera pallida and 
Drosera sulphurea, “ close their leaves upon insects with 
“great rapidity: and the same phenomenon is mani- 
“fested by an Indian species, D. lunata, and by several 
“of those of the Cape of Good Hope, especially by 
“D. trinervis.” Another Australian species, Drosera 
heterophylla (made by Lindley into a distinct genus, 
Sondera) is remarkable from its peculiarly shaped 
leaves, but I know nothing of its power of catching 
insects, for I have seen only dried specimens. The 
leaves form minute flattened cups, with the footstalks 
attached not to one margin, but to the bottom. The 
* ¢Gardener’s Chronicle,’ 1874, p. 209. 
