Francis E. Lloyd — 88 — Carnivorous Plants 



physiologically is hard to resist in view of their number and general 

 relations. Goebel's idea that they are water pores seems the most 

 acceptable, that is, that they pour a fluid into the pitcher cavity; but 

 this fluid may contain substances in solution, more Hkely enzymes, 

 possibly one or more enzymes different from those of the glands. I 

 did a simple experiment with living pitchers to test Goebel's idea. 

 Halving a pitcher longitudinally, and cleaning it out thoroughly, I 

 placed it in contact, by its outer surface, with water in a closed damp 

 chamber. In the course of some hours beads of moisture appeared 

 from the mouths of the glands, larger ones from the larger glands but 

 none from the stomata, at least in appreciable quantities. This seems 

 to indicate that water excretion by the "water pores" plays a minor 

 role, if any, and that Dakin's suggestion that their function is that of ab- 

 sorption cannot be dismissed without further examination. Any in- 

 terpretation of the activity of these stomata must take into account 

 the constant presence of a large amount of starch in large grains in the 

 mesophyll of the glandular patches. 



The problem of digestion by the pitchers has been examined in any 

 thoroughgoing way only by Daken (191 8), who spent a vacation at 

 Albany, W. A., making as careful a study as he could, under laboratory 

 conditions. To be sure, Dickson (1878) had reported that Lawson 

 Tate had examined into the matter somewhat and had found that 

 "fluid taken from virgin or unopened pitchers" showed "that it ex- 

 erted a similar digestive action on animal substances to that exhibited 

 by the Nepenthes pitcher, etc." Dakin made use only of the fluid 

 from opened pitchers, which did not surprise me when on careful ex- 

 amination of all the unopened pitchers which I could come by on my 

 own visit to Albany, I found no one of them containing any sign of 

 fluid, a matter of disappointment as I had intended to conduct experi- 

 mentation on such fluid if it could be found. Dakin's results are 

 as follows: He found that the pitchers capture many insects, notably 

 ants, as others had found. They are represented usually by fragmen- 

 tary remains of the chitinous parts. Even the very small pitchers, as I 

 have previously said, catch small insects. That the soft parts undergo 

 dissolution in some sort is at once evident. But, Dakin asked, is this 

 the result of digestion by enzymes secreted by the pitcher glands, or of 

 bacterial action, or of both ? Fibrin was his test substrate. The ex- 

 periments were conducted with pitcher fluid with an antiseptic (HCN) 

 and with and without weak acid (HCl) or alkaK. The specific 

 results which he records showed that pitcher fluid in vitro in the 

 presence of added acid does digest fibrin, and that it contains a di- 

 gestive ferment which will break up proteins into peptone-like bodies 

 in the presence of acid. Since non-acidulated pitcher fluid does not act 

 thus, it cannot be concluded that this process actually takes place in 

 the pitchers under normal circumstances. Pitcher fluid alone procures 

 dissolution of fibrin with the odor of putrefaction. Dakin admits the 

 possibility that digestion by pitcher fluid may, however, take place 

 very slowly in the pitchers. 



He raises, however, the question of the usefulness or necessity of 

 this to the plant. He kept plants under his eye in the laboratory 

 where they grew thriftily and flowered without having been supplied 



