CHAP. XV. ON TIIE DROSERACE^. 361 



tentacles of Drosera, with their glands aborted, but their 

 sensitiveness retained. Under this point of view we 

 should bear in mind that the summits of the tentacles 

 of Drosera, close beneath the glands, are sensitive. 



The three most remarkable characters possessed by 

 the several members of the Droseracese consist in the 

 leaves of some having the power of movement when 

 excited, in their glands secreting a fluid which digests 

 animal matter, and in their absorption of the digested 

 matter. Can any light be thrown on the steps 

 by which these remarkable powers were gradually 

 acquired ? 



As the walls of the cells are necessarily permeable 

 to fluids, in order to allow the glands to secrete, it is 

 not surprising that they should readily allow fluids to 

 pass inwards ; and this inward passage would deserve 

 to be called an act of absorption, if the fluids com- 

 bined with the contents of the glands. Judging from 

 the evidence above given, the secreting glands of 

 many other plants can absorb salts of ammonia, of 

 which they must receive small quantities from the rain. 

 This is the case with two species of Saxifraga, and the 

 glands of one of them apparently absorb matter from 

 captured insects, and certainly from an infusion of raw 

 meat. There is, therefore, nothing anomalous in the 

 Droseraceee having acquired the power of absorption 

 in a much more highly developed degree. 



It is a far more remarkable problem how the 

 members of this family, and Pinguicula, and, as Dr. 

 Hooker has recently shown, Nepenthes, could all have 

 acquired the power of secreting a fluid which dis- 

 solves or digests animal matter. The six genera of 

 the Droseraceae have probably inherited this power 

 from a common progenitor, but this cannot apply to 



