436 HEPBURN— BIOCHEMICAL STUDIES 



quantity of egg-white was used, the unabsorbed products of digestion 

 accumulated, and the pitcher was invaded by bacteria. 



When a sterile solution of egg-white, prepared as follows, was intro- 

 duced into the pitchers, digestion occurred; and bacterial invasion and 

 putrefaction were rarely noted. Ten cc. of white of egg and 90 cc. of 

 water were shaken together, to break up the membranes in the white 

 and to dissolve the albumin. The solution was filtered and 0.1 milli- 

 gram of ferrous sulphate was added, i.e., 2 drops of a freshly prepared, 

 0.1 percent solution of ferrous sulphate. If the egg had not been fresh, 

 more iron was added, but never an amount in excess of 1 milligram of 

 ferrous sulphate. The solution was then boiled; it usually remained 

 clear and limpid, but at times showed a faint opalescence. After con- 

 ducting a digestion experiment with this solution as the substrate, the 

 lindigested albumin was removed by the following procedure. An alka- 

 line salt was added to the solution, which was then acidified very quickly, 

 and the albumen was coagulated with heat. 



In most vigorous pitchers, all the protein was digested at the end of 

 two days. Thus 5 cc. of the solution of egg-white, described above, was 

 introduced into a pitcher. At the end of two days the pitcher liquor 

 gave no precipitate on neutralization, and on boiling in the presence of 

 salts or of acids; it yielded merely a trace of a precipitate with the follow- 

 ing reagents:— potassium mercuric iodide, acetic acid and potassium 

 ferrocyanide, phosphomolybdic acid. 



The plant itself played an important role in the digestion. Experi- 

 ments were made in vitro with liquor from both unopened and open 

 pitchers, using- chloroform as a bactericide. Absolutely no digestion 

 of the substrate occurred. In one experiment, liquor, which possessed 

 digestive power while in the pitcher, digested the substrate in vitro; the 

 albumen disappeared, and much albumose (proteose) and possibly a 

 httle peptone were formed. Separation of the pitcher from the plant 

 during the course of digestion inhibited the digestion of the albumin. 



Clautriau also conducted experiments at Brussels on Nepenthes 

 which had been cultivated in greenhouses. 



He used the following technique in studying the products of the 

 proteolysis. After digestion, the solution was neutralized with dilute 

 sodium hydroxide solution in order to separate the syntonin (acid meta- 

 protein), which was collected on a filter. To the filtrate were added an 

 equal volume of saturated solution of sodium chloride and a trace of 

 acetic acid; the solution was boiled to coagulate the albumin, which was 

 then removed by filtration. The filtrate was saturated, while hot, with 



