Francis E. Lloyd — 48 — Carnivorous Plants 



Digestion and Absorption. — Edwards (1876) and Goebel were of 

 the opinion that true digestion, that is, by means of a secreted enz3mie, 

 does not take place in Darlingtonia. More recently Hepburn and 

 his collaborators St. John and Jones (1920, 1927) examined the fluid 

 of unopened, cotton-plugged and open pitchers with regard to its 

 effect chiefly on carmine fibrin and fibrin in the presence of a bacteri- 

 cide (0.2% trikresol). Of a total of 57 experiments in the laboratory 

 and field, none gave a definitely positive result, occasional, very slight 

 aberrancies being due probably to the presence of bacterial ferments. 

 On anatomical grounds this is to be expected, though as above noted, 

 Batalin made a suggestion that the non-cuticularized cells of the 

 depths of the pitcher might take over the function of the glands. But 

 that the function of the secretion of a protease could be one seems, 

 in view of the above cited results, to be out of the question. That 

 insects are disintegrated by bacteria is obvious, and that their products 

 are available as nutriment to the plant is indicated by the fact that 

 absorption of various substances can and does take place as shown 

 also by Hepburn and his colleagues, and as would appear to be the 

 case in view of the non-cutinized tissues of the pitcher through which 

 methylene blue readily passes. Hepburn, St. John and Jones showed 

 that water is absorbed, and dissolved lithium was found to have been 

 taken up by the tissues. When various nitrogenous substances were 

 introduced, both these and the solvent were absorbed, but in the 

 presence of a phosphate buffer the water might increase though the 

 compounds were absorbed. Mrs. Austin had found (1876) that when 

 stimulated by the introduction of bits of meat, the amount of fluid 

 increased in the pitchers. Her results were quoted by Asa Gray 

 (1876). Though the experiments were done in the field, there is as- 

 surance of the exclusion of rain which, if any fell, which is quite un- 

 likely, could gain no entrance into the hooded pitchers. Hepburn 

 et al. investigated this point, also in the field (Plumas Co., Calif.) and 

 found that when milk was introduced into the pitchers, there was in- 

 variably an increase in the amount of fluid ranging from 20 to 1242 

 per cent in periods of 1-7 days. They studied 77 pitchers, and the 

 amount of increase of volume varied independently of the time, so 

 that some pitchers were much more active than others. When beef 

 broth was used, there was an increase of from 302 to 387 per cent in 

 fluid content in five days. When bits of meat were used the results 

 depended on whether the meat was cooked or raw. If cooked there was 

 little if any increase, because only small patches of the surface were 

 affected. If raw, an increase of volume of from 48 to 157 per cent 

 was observed. No results were obtained with raw or coagulated egg- 

 white, nor with cheese, casein or fibrin "possibly for the same reason 

 as with meat." When acids and alkalis in very dilute solutions were 

 introduced, there was no very "marked tendency" for the volume of 

 fluid to "increase or decrease", but it was noted that, as in the human 

 stomach, the fluid returned to neutrality whatever the nature of the 

 introduced reagent. 



Has the fluid of pitchers the power of wetting insects, when im- 

 mersed, more than pure water? While positive evidence was ob- 

 tained for other species of Sarraceniaceae, that from Darlingtonia, 

 from experiments done in the field, was purely negative. 



