860 CONCLUDING REMARKS Chap. XV. 



power was transferred to the basal parts of tlie 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, Eoridula, and Byblis, which appear to have 

 retained a prinjordial 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 excej)tion 

 of one species, Drosera hinata. 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 papillae. 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 rotundifoUa. The footstalks of this 

 latter species bear multicellular hairs, which we have 

 good reason to believe represent aborted tentacles. 



The parent form of Dionaea 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 uppef 

 surface. I think so because the marginal spikes of 

 Dionaea 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 



