ON THE DIGESTIVE FEBMENT OF NEPENTHES. 427 



a the Digestive Ferment of Nepenthes. By S. H. Vrfo:s, B.A., 

 Fellow of Christ's College, Cambridge. Communicated by W. 



M 



Gardens, Kew. 



[Bead June 15, 1876.] 



I. 



The publication of Dr. Hooker's address at the Belfast Meeting 

 of the British Association for the Advancement of Science 

 (August 1874), and of Mr. Darwin's book on Insectivorous 

 Plants, has given rise to several investigations into the nature of 

 the phenomena described in those works. The questions at issue 

 are these : — (1) as to whether the solution of the proteids therein 

 described was effected by a process of true digestion ; and (2) if 

 so, what relation exists between the processes of digestion occur- 

 ring in plants and those with which we are acquainted in animals. 



The first attempt to answer these questions was made by Dr. 

 Lawson Tait. In a paper read before the Birmingham Natural- 

 History Society on June 17, 1875*, Dr. Tait announced that he 

 bad been able to separate a substance closely resembling pepsi 

 from the secretion of Drosera dicliotoma ; and subsequently in 

 1 Nature,' July 29, 1875, he stated that he had succeeded in ob- 

 taining a similar substance from the fluid taken from the pitchers 

 of various species of Nepenthes. In some of its properties the 

 substance obtained from Drosera, to which Dr. Tait gives the 

 name Droserine, resembles pepsin, more especially in its solubility 

 in glycerin. Unfortunately, however, Dr. Tait seems to have in- 

 stituted no experiments which clearly prove that the substance 

 which he had isolated was in fact a digestive ferment — as, for 

 instance, a test of the digestive power of its glycerin solution on 

 some proteid. Under these circumstances, the isolation of the 

 ferment can hardly be regarded as an accomplished fact, espe- 

 cially as the chemical method adopted by Dr. Tait in his researches 

 is not wholly satisfactory. 



The next series of experiments on this subject with which I am 

 acquainted are those of Eiess and Will of Erlangent, which were 

 made upon Drosera rotundifolia. Their object was to show, if 

 possible, that the leaves of this plant contained in their gland- 



* 



* Abstracted in ■ Nature/ July 29, 1875. 

 t Bot. Zeitung, Oct. 29, 1875, no. 44. 



