362 CONCLUDING REMARKS CHAP. XV 



Pinguicula or Nepenthes, for these plants are not at all 

 closely related to the Droseracere. But the difficulty 

 is not nearly so great as it at first appears. Firstly, the 

 juices of many plants contain an acid, and, apparently, 

 any acid serves for digestion. Secondly, as Dr. Hooker 

 has remarked in relation to the present subject in his 

 address at Belfast (1874), and as Sachs repeatedly 

 insists,* the embryos of some plants secrete a fluid 

 which dissolves albuminous substances out of the 

 endosperm ; although the endosperm is not actually 

 united with, only in contact with, the embryo. All 

 plants, moreover, have the power of dissolving albu- 

 minous or proteid substances, such as protoplasm, 

 chlorophyll, gluten, aleurone, and of carrying them 

 from one part to other parts of their tissues. This 

 must be effected by a solvent, probably consisting of 

 a ferment together with an acid.f Now, in the case of 

 plants which are able to absorb already soluble matter 

 from captured insects, though not capable of true 

 digestion, the solvent just referred to, which must be 

 occasionally present in the glands, would be apt to 

 exude from the glands together with the viscid secre- 

 tion, inasmuch as endosmose is accompanied by 

 exosmose. If such exudation did ever occur, the 

 solvent would act on the animal matter contained 

 within the captured insects, and this would be an 

 act of true digestion. As it cannot be doubted 

 that this process would be of high service to plants 



* 'Traite de Botanique,' 3rd Berlin, 1874, p. 1478), who, with 



edit. 1874, p. 844. See also for the aid of Dr. H. Will, has ac- 



following facts pp. 64, 76, 828, tually made the discovery that the 



831. seeds of the vetch contain a fer- 



f Since this sentence was writ- meut, which, when extracted by 



ten, I have reseived a paper by glycerine, dissolves albuminoua 



Gorup-Besanez ('Berichte der substances, such as fibrin, and 



Deutschen Chem. Gesel^chaft,' converts them into true peptonea 



