28-4 CONCLUDING REMARKS. CHIP. XII 



moved towards the middle of the lower surface, for there aro 

 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 Dmsent, 

 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. 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 described, it is said* that two other 

 species from this country, namely Drosera pallida and 

 Drosera sulpliurea, " 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 

 lieteropliylla (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 



* ' Gardner's Chronicle,' 1874, p. 200. 



