Chap. XII.] CONCLUDING REMARKS. 231 



rendered more serviceable to the plant; for they are not long 

 enough to bend round the margin of the leaf so as to reach an 

 insect caught on the upper surface. Nor would it have been of 

 any use if these tentacles could have moved towards the middle of 

 the lower surface, for there are no viscid glands there by which in- 

 sects 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 chapter 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 numer- 

 ous insects, which serve as nutriment. Therefore it seems that 

 Drosera binata has retained remnants of certain ancestral charac- 

 ters 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. From what we have now seen, 

 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 de- 

 scribed, 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 phe- 

 nomenon is manifested by an Indian species, D. lunaia, and 

 by several of those of the Cape of Good Hope, especially by 

 D. trinervis." Another Australian species, Drosera hetero- 

 phylla (made by Lindlcy into a distinct genus, Sondera) is 

 remarkable from its peculiarly shaped leaves, but I know 

 nothing of its i>ower 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 inner surface and the edges of the cups are 

 studded with tentacles, which include fibro-vascular bundles, 

 rather different from those seen by me in any other species: 

 for some of the vessels are barred and punctured, instead of 

 being spiral. The glands secrete copiously, judging from 

 the quantity of dried secretion adhering to them. 



* Gardener's Chronicle,' 1874, p. 209. 



