Francis E. Lloyd — 34 — Carnivorous Plants 



was probably neutralized by the acid proper to the fluid which had 

 been shown to be present. There was no marked difference between 

 the fluid of open and of closed pitchers. It was concluded that a 

 protease was present which, however, acted best in an alkaline medium. 



Edestin was slightly attacked by the fluid of open pitchers. Casein 

 was digested completely in 2-8 hours at 37.5° C, and coagulated 

 egg-white, in the absence of acid or alkali, was not attacked, nor was 

 it in the presence of acid, but, on the addition of alkah, "incipient 

 digestion was noted in 24 hours, marked digestion in 48 and 144 

 hours and advanced digestion in 168 and 216 hours respectively" for 

 two experiments. 



S. rubra. — Only a single sample of fluid was available, but this 

 on division showed that in the presence of alkali digestion proceeded 

 rapidly, o.oi gram of fibrin being completely digested in 1.3 cc. of 

 fluid in 2 hours. In the part with acid added "partial solution was 

 noted at the end of 9 days, complete solution at the end of 50 days." 



S. minor. — Experiments were done in the field. No digestion oc- 

 curred in 30 days (trikresol present) in the absence of acid or alkali, 

 but it did occur when either acid or alkali was added to the fluid, 

 but less vigorously in the alkaline, than in the acid medium. This 

 species therefore stands in contrast to the others aforementioned. 



S. psittacina. — Field observation showed that fluid was being se- 

 creted in the pitchers, but in such small amounts that it had to be 

 collected by dilution with water (0.5 cc. in each of 50 pitchers free 

 of insects). The results were inconclusive, but indicated that a pro- 

 tease is present which is active in the presence of acid. 



Sarracenia purpurea. — The secretion in this species is very small 

 in amount, being found as beads of moisture on the walls. Experi- 

 ments were done by flushing the pitchers, emptying, and adding 10 

 to 15 cc. of water to each pitcher. After some days this was removed 

 and tested. The fluid thus obtained showed an ability when alka- 

 line to digest fibrin to a marked extent in 8, 24, 72, and 87 hours 

 (4 samples), and completely in 42, 48, 120, and 135 hours, respectively. 

 Three other experiments gave positive results in 42 and 87 hours. 

 In acid, the results were equivocal. 



The general conclusions reached by Hepburn and his colleagues 

 are that a protease is present in all the Sarraceniae, but that in most 

 cases it acts best in an alkaline medium. In some cases, however, it 

 acts in an acid medium. 



It was shown experimentally that pitcher fluid retains its power 

 of digestion after being kept at room temperature for as long as 370 

 days, either with or without a bactericide; and that this is also re- 

 tained on dilution, which is of importance in view of the fact that 

 dilution by rain may always be expected in the habitat. In contrast 

 with Nepenthes, neither mechanical nor food stimulation was found 

 to have any effect. 



In the fluid of closed pitchers there is evidence that there are both 

 invertase and lipase, while maltase, emulsin, diastase, urease, and 

 esterase were present. It will be recalled that Zipperer claimed the 

 digestion of starch and Robinson that of sucrose and starch. 



It is generafly understood that the water of swamps and sandy 



