193 



IV. Effects on Protein 

 Fibrin. — Water which had been left in the pitchers of Sarra- 

 ce7iia six days was removed and placed in bottles to each of 

 which a granule of fibrin was added. As checks, toluol was 

 added to some of these, dilute acid to others, and dilute alkali to 

 a third set, the acidity or alkalinity being in each case below the 

 harmful point as determined by the earlier experiments. Toluol 

 was added to a portion of the acid and alkaline mixtures. The 

 result was quite uniform, for the fibrin granule remained appar- 

 ently unchanged in each liquid. 



General Conclusions 

 The results of the above experiments may be summarized as 

 follows : 



1. The pitchers of Sarracenia purpurea can adapt themselves 

 to solutions of very different osmotic strengths. 



2. They give out an enzyme which hydrates sucrose and 

 starch to reducing materials, presumably simple sugars. 



3. They have no fat-digesting power. 



4. They do not secrete a protein-dissolving enzyme. 



In the tests which were made upon the pitchers of Nepenthes 

 the resistance to solutions of marked difference in osmotic 

 strength was shown to be the same as in the case of Sarracenia. 

 The plants differed in that Nepenthes did not give out into the 

 pitcher cavity any enzyme capable of hydrating sugar and starch, 

 whereas Sarracenia did. The experiments as to protein digestion 

 in Nepenthes were inconclusive, but they were not repeated partly 

 because of insufficient material and partly because the demon- 

 stration of the existence of a protein-dissolving enzyme in Nepen- 

 thes by Vines (Ann. Bot. 12 : 545. 1898) was accepted as final. 



Sarracenia purpurea belongs to the class of plants which, like 

 the bromeliads of the tropics or our northern catch-fly, illustrates 

 a mal-adaptation between plants and animals, for while they 

 serve as traps for insects they are neither harmed nor benefited 

 by them, unless the number be very great. In the sphagnum 

 bogs where Sarracenia grows, the concentration of salts and 

 nitrogenous matter about its roots is so great as to place them 



