432 HEPBURN— BIOCHEMICAL STUDIES 



Tischutkin maintained that the digestion of protein in the liquor of 

 insectivorous plants is produced exclusively by the vital activity of 

 micro-organisms, which are always present in the secretion of the fully 

 developed plant, entering from the air and also with the bodies of the 

 insects, etc. The role of the insectivorous plants is therefore limited; 

 they secrete a medium favorable for the activity of the peptonizing micro- 

 organisms, and they make use of the products of this activity. 



Goebel (11) made an elaborate research on the pitcher liquor. Pitch- 

 ers of Nepenthes paradisiaca (a hybrid) contained a clear, colorless, taste- 

 less fluid free from insects. Fibrin flocks were placed in the pitchers, 

 and also in water as a control. In both cases, after 6 days, the flocks 

 had been disintegrated into little shreds, and innumerable bacteria were 

 present. The liquor, in all the experiments, was either neutral or very 

 faintly alkahne, and contained no peptone. The liquor from the pitchers 

 gave no color with Nessler's reagent; the solution from the flasks, which 

 contained water and fibrin, gave a strong yellow color with this reagent. 

 Hence, in the pitchers, the nitrogenous compounds produced by the 

 proteolysis of the fibrin were absorbed, either as ammonia or as some 

 other compound. 



Liquor was removed from the pitchers, in which the fibrin had been 

 digested, and was sown on nutrient gelatin. The gelatin became lique- 

 fied to a marked degree in 2 days and acquired a green fluorescence 

 which is characteristic of Bacillus fluorescens liquefaciens. Neither 

 bacteria nor moulds were found when liquor from unopened pitchers was 

 inoculated into the gelatin. 



Liquor was collected from unopened pitchers of N. paradisiaca; it 

 exerted very little digestive action after 0.2 percent hydrochloric acid 

 had been added, forming very little peptone; therefore very little enzyme 

 was present. 



The absorption of ammonia by the pitcher was demonstrated by the 

 following procedure. A definite volume of aqueous solution of ammonia 

 (containing 1 part of ammonia in 20,000 parts of solution) was placed 

 in a pitcher, an equal volume of the solution was placed in a glass vessel 

 in the Nepenthes house as a control. Twenty-four hours later, the volume 

 of Hquid within the pitcher was practically unchanged. However, 

 Nessler's reagent produced no precipitate with the contents of the pitcher, 

 and formed a thick precipitate with the control experiment; therefore 

 ammonia had been absorbed by the pitcher. Further experiments 

 demonstrated that one-half of the ammonia was absorbed during the 

 first three hours, and that all the ammonia had been absorbed at the end 



