OF INSECTIVOROUS PLANTS 441 



1.5 grams, dipotassium phosphate 1.5 grams, magnesium sulphate 1.5 

 grams, ferrous sulphate a trace, water 6000 cc.) caused a withering of 

 the tissues on about the eighth day. When a dilute solution of Liebig's 

 meat extract was introduced, and the plants then observed for a period 

 of two weeks, the contents of the pitchers did not become foul, and the 

 pitchers did not decay. A 10 percent solution of glucose, kept in the 

 pitchers for 4 da}s, apparently had no harmful effect on the plant; the 

 solution retained its power to reduce Fehling solution. 



Robinson also made tests concerning the secretion of enzymes by the 

 pitchers. A 10 percent solution of sucrose, which had been in the 

 pitchers for 4 days, failed to reduce Fehling solution, whence it was 

 inferred that an invertase is not secreted by the pitchers. A thin starch 

 paste was kept in the pitchers for 4 days; it then had no reducing action 

 on Fehling solution, and " the iodine test showed that the starch granules 

 in the paste had not been broken down "; therefore the pitchers do not 

 secrete an amylase (diastase). 



Neutral olive oil and water were mixed in the proportion of 0.4 cc. 

 of oil and 9.6 cc. of water. After the mixture had been thoroughly 

 shaken, it was introduced into pitchers, and permitted to remain in them 

 for a period of from 4 to 7 days, then removed and titrated with 0.01 N 

 potassium hydroxide solution, using phenolphthalein as an indicator. 

 Control experiments were carried out (a) with the emulsion of oil in 

 vitro, and (b) with the emulsion plus toluol in the pitchers. The results 

 indicated that hydrolysis of the oil did not occur, and that the pitcher 

 does not secrete lipase. Tap water, which had been kept in the pitchers 

 for 1 day, was used in an experunent with ethyl butyrate; 2 cc. of this 

 water and 4 drops of the ester were allowed to react at room temperature 

 for 24 hours; the hydrolysis of the ester was determined by titration with 

 0.01 N fixed alkaline hydroxide, using phenolphthalein as an indicator. 

 Enzymic cleavage of the ester was not detected, hence an esterase was 

 not present. 



Jenny Hempel (15) found that "the sap of the stimulated pitcher of 

 Nepenthes gives values for the hydrogen ion concentration greater than 

 10"", but unstimulated pitchers give no definite value. " 



Shibata and Nagai (16) noted the presence of flavone in the leaves 

 and the flowers of Nepenthes phyllamphora Willd. More flavone was 

 present in N. phyllamphora, growing in the open on the island of Yap, 

 than occurred in N. Mastersiana, growing under glass at Tokyo. 



Pfeffer (17) has suggested that the insectivorous plants derive both 

 nitrogen and phosphorus from their prey. 



