THE PITCHER LIQUOR OF NEPENTHES. 127 



A goodly number of bacteria were present in the liquor of 

 pitchers which had partly opened, but had not yet been invaded by 

 insects. 



The bacterial content of the liquor of open active pitchers, which 

 contained insect remains, was quite high — from 48,000 to 8,000,000 

 per c.c. of liquor ; the organisms were rods. These bacteria lique- 

 fied gelatin, and formed colonies on solid media (agar) in which the 

 sole source of carbon and nitrogen was either a protein or a simple 

 organic compound. They usually digested the protein (casein, egg 

 albumen, carmine fibrin, edestin, Jacoby's ricin, protein from aleu- 

 ronat), but at an exceedingly slow rate. They decomposed the 

 simple nitrogenous organic compounds (glycocoll, acetamide, as- 

 paragin, ammonium lactate), frequently producing an odor like that 

 of ammonia and amines, and always imparting an alkaline reaction 

 to the medium ; this reaction subsequently changed to acid in some 

 experiments, but the colonies always remained alkaline. The bac- 

 teria did not produce either tryptophane or indol from aleuronat 

 protein, when sown on a medium in which the latter was the sole 

 source of carbon and nitrogen. Organisms of the colon-aerogenes 

 group were present ; on the average, each c.c. of pitcher liquor con- 

 tained 10,000 organisms of this group. 



The chemical and bacteriological studies taken together lead to 

 these conclusions. 



The protease of the pitcher liquor is the chief factor in the diges- 

 tion of the insects in the pitcher. The bacteria, which occur in the 

 liquor of opened pitchers, play merely a secondary part, as is shown 

 by the slowness with which they digested proteins. 



The bacteria and the NepentJies plant live in symbiosis ; the bac- 

 teria obtain their food from the digested insects and assist, to a 

 limited extent, in the digestion of the insects. 



The tissue enzymes of the insects, of course, may assist in the 

 digestion by causing the insects' tissues to undergo autolysis. 



Note on the Biochemistry of the Pitcher Liquor of 

 Sarracenia. 



Closely related to the family Nepenthacece, with its single 

 genus Nepenthes, is the family Sarraceniacecc, consisting of three 



