Chap. XV.] DROSERACE^. 289 



There can hardly be a doubt that all the plants belonging 

 to these six genera have the power of dissolving animal mat- 

 ter by the aid of their secretion, which contains an acid, 

 together with a ferment almost identical in nature with 

 pepsin; and that they afterwards absorb the matter thus 

 digested. This is certainly the case with Drosera, Dro- 

 sophyllum, and Dionaja; almost certainly with Aldrovanda; 

 and, from analogy, very probable with Roridula and Byblis. 

 We can thus understand how it is that the three first-named 

 genera are provided with such small roots," and that Aldro- 

 vanda is quite rootless; about the roots of the two other 

 genera nothing is known. It is, no doubt, a surprising fact 

 that a whole group of plants (and, as we shall presently see, 

 some other plants not allied to the Droseracese) should sub- 

 sist partly by digesting animal matter, and partly by de- 

 composing carbonic acid, instead of exclusively by this latter 

 means, together with the absorption of matter froni the soil 

 by the aid of roots. We have, however, an equally anomalous 

 case in the animal kingdom; the rhizocephalous crustace- 

 ans do not feed like other animals by their mouths, for they 

 are destitute of an alimentary canal; but they live by ab- 

 sorbing through root-like processes the juices of the animals 

 on which they are parasitic' 



Of the six genera, Drosera has been incomparably the 

 most successful in the battle for life; and a large part of its 



[Fraustndt (Dissertation, by absorption through branching 

 Breslau, 1876) shows that the root-like processes. If one rare 

 roots of DIousea are by no means clrrlpede, the Anelasma aqualicola, 

 small. In another Breslau DIs- had become extinct, it would 

 sertatlon (1887) Otto Peuzig have been very ditficult to conjee- 

 shows that the roots of Droxo- ture how so enormous a change 

 phyllum luHitanictim are also well could have been gradually ef- 

 developed. Pfeffer ('Landwirth. fected. But, as Fritz MilUer re- 

 Jahrbucher,' 1877) points out that marks, we have In Anelasma an 

 the argument from the small de- animal In an almost exactly In- 

 velopment of roots In some car- termedlate condition, for it has 

 nlvorous plants Is. valueless, be- root-like processes embedded In 

 cause the same state of things is the skin of the shark on which It 

 found In many marsh and aquatic Is parasitic, and Its prehensile 



Slants which neither catch nor cirri and mouth (as described In 

 Igest Insects. F. I).] my monograph on the Lepadlda^, 

 ' Fritz MUUer. ' Facts for Dar- ' Ray Soc.' 1851, p. 1(59) are In a 

 win,' Eng. trans. 18(!9, p. i:{0. most feeble an<i almost rudl- 

 The rhizocephalous crustaceans nientary condition. Dr. K. Koss- 

 are allied to the clrrlpe<les. It Is mann has given a very Interest- 

 hardly possible to Imagine a Ing discussion on this subject In 

 greater difference than between his ' Suctoria and Lepadidie," 

 an animal with prehensile limbs, 187.3. See. also. Dr. Dohrn, ' Der 

 a well-constructed mouth and all- Urspruug der Wirbelthlere,' 1875, 

 mentary canal, and one destitute p. 77. 

 of all these organs and feeding 



