Francis E . Lloyd —70— Carnivorous Plants 



secreted by the glands, but that there is a direct response to the 

 presence of the material to be digested. He saw evidence also of 

 antiseptic action in that odor was not developed so rapidly in the 

 pitcher fluid as in water. His general conclusion may be stated in his 



own words: " it would appear probable that a substance acting 



as a pepsine does is given off from the inner wall of the pitcher, but 



chiefly after placing the animal matter in the acid fluid; " In 



the following year (1875) Lawson Tate announced that he had suc- 

 ceeded in separating a substance "closely resembling pepsin" from 

 the secretion of Drosera dichotoma and a little later he obtained a sim- 

 ilar substance from the fluid taken from the pitchers of several species 

 of Nepenthes, but did not subject these extracts to the appropriate 

 tests. The preparations seem to have been glycerin extracts, in which 

 both were soluble. At the same time Rees and Will of Erlangen 

 (1875) made preparations of Drosera, drying the leaves with absolute 

 alcohol and extracting the ground material with glycerin. Such ex- 

 tracts, but only when slightly acidified with HCl (.2%), caused the 

 disappearance of swollen fibrin at 40 degrees in 18 hours, peptones 

 being produced, thus confirming the work of Darwin on Drosera. At 

 about the same time von Gorup-Besanez (1874) studied the fluid of 

 Nepenthes pitchers, and found that when he subjected shreds of fibrin 

 to the naturally acid secretion, they were nearly digested in an hour at 

 40 degrees, peptones then being present. Additional acid as above 

 accelerated the action. 



Von Gorup and Will (1876) investigated further. They compared 

 the behavior of the fluid from stimulated pitchers (to which insects 

 had had access) with that from unstimulated pitchers. The former 

 was filtered and tested with acidulated fibrin, raw meat, coagulated 

 egg-white, legumin and gelatin, obtaining positive evidence in all cases 

 with the Biuret reaction, the gelatin excepted. This yielded a non- 

 jelHng gelatin-peptone. The fluid of unstimulated pitchers was found 

 to fail to act unless acidified, but responded in the presence of HCl, 

 formic, malic, citric, acetic and propionic acids. The efficiency of these 

 was various, formic acid being very active ("fast momentan"), followed 

 by malic, citric, acetic and propionic in the order named. The length 

 of time in which positive results were obtained, as indicated by the 

 Biuret reaction, varied from 10 minutes to three hours or more accord- 

 ing to the activity of the acid and the temperature. 



Vines was busy at the same time. Following the method of Rees 

 and Will, he (1877) alcohol-dried pitcher walls bearing the glands of 

 Nepenthes and ground and extracted them with glycerin. In testing 

 his extracts he used the following method. In each of three test tubes 

 he placed (i) extract acidified; (2) extract only and (3) acid only, and 

 added a bit of swollen fibrin and kept the tubes at 40 degrees. Only 

 the first of the preparations gave a positive result and a peptone reac- 

 tion could be detected; the other two were negative. Vines noticed 

 that the pitcher fluid in von Gorup-Besanez' experiments appeared to 

 be more active than his own extracts. Following the lead of Ebstein 

 and Gruetzner and of Haidenhain (through Vlnes), who had ob- 

 tained more active extracts of animal glands by previous treat- 

 ment with acid. Vines then treated the pitcher wafls bearing glands 



