440 HEPBURN— BIOCHEMICAL STUDIES 



upon the glands of the pitcher wall beneath the roof-like epidermal 

 structures. 



(3) Insects, which enter the pitcher liquor, can be completely dis- 

 solved with the exception of their chitin plates; the latter are found as a 

 sediment. 



Fenner considered it a question for further study whether (a) the 

 dissolved products of the digestion were withdrawn from the liquor and 

 absorbed by the glands, or (b) their solution in the liquor was absorbed 

 as such by the glands. Apparently the same glands, that secrete the 

 pitcher liquor and the digestive mucilage, absorb the products of diges- 

 tion. 



Abderhalden and Teruuchi (28) studied the action of the pitcher 

 liquor of Nepenthes on the dipeptide glycyW-tyrosin. This peptide is 

 quite soluble in water, and is not cleaved by pepsin-hydrochloric-acid 

 but is readily spht by tr}^sin into its components, glycine (glycocoll) and 

 /-tyrosin; the latter compound is very difScultly soluble in water, and 

 precipitates. 



Liquor was obtained from pitchers with closed lids, and from open 

 pitchers which appeared to contain no very large quantity of condensa- 

 tion water. It was viscous, neutral in reaction, and exerted a very slow 

 but distinct proteolytic action on fibrin flocks; after digestion for 3 days, 

 the fluid was removed by filtration and then gave a distinct biuret 

 reaction. 



One gram of glycyl-/-tyrosin was dissolved in 10 cc. of liquor, collected 

 from several pitchers,- and toluene was added as a bactericide. The 

 solution was kept at room temperature for 7 days; a slight cloudiness 

 occurred, but no precipitate formed. Then the solution was transferred 

 to an incubator; the opalescence did not increase; and a precipitate did 

 not separate, even when the solution was evaporated to half its original 

 volume. 



The conclusion was drawn that the protease of Xepenthes is not a 

 tr}'psin. ''It therefore seems that the flesh-eating plants, Nepenthes, 

 do not act through a tr>'psin-like enzyme. We do not venture to record 

 our finding as a certainty, since from lack of material, it was not possible 

 for us to repeat the experiment under different conditions. " 



Robinson (14) introduced various solutions into pitchers of Nepenthes 

 distiUatoria and noted their,action upon the pitchers. A dilute (M/1024) 

 solution of potassium nitrate had exerted no injurious action at the end 

 of 9 days, but the pitcher began to wither at the end of 12 days. The 

 nutrient solution of Sachs (calcium nitrate 6 grams, potassium nitrate 



