448 BIOLOGIC RELATIONS BETWEEN PLANTS AND ANTS. 



bacterial or otherwise, of tlieir carcasses, be useful to the plant — that is 

 to say, absorbed ? The internal walls of the pitcher are not at all suited 

 for the absorption of liquids or the secretion of a digestive fluid. The 

 absence of all kinds of glands is easy to demonstrate, and the entire 

 surface of the epidermis is covered with a waxy coating. In addition, 

 abundant stomata exist there which certainly does not indicate an 

 organ for the absorption of liquids. This waxy coating is raised in 

 minute turrets around each of the stomata, and the small chamber thus 

 formed is constantly filled with air (Treub). These are features that 

 contradict in the clearest manner the absorption of solid nutritive 

 substances by the internal surface of the pitcher. 



We may then suppose, with Delpino, that the ascidiferous Dischidias 

 are not carnivorous plants in the strict sense of the word. Perhaps, 

 then, the true function of the ascidia is "to prepare a liquid animal 

 fertilizer for the purpose of nourishing the much ramifying adventitious 

 roots that have introduced themselves into the pitchers." As a corol- 

 lary we would have to admit that the pitchers belong to that class 

 whose "immediate function is to kill by drowning the small animals 

 that enter them." 



Let us commence by examining this last hypothesis. If it be correct 

 the lutchers ought all to contain liquid. Now, that is not the case, 

 for, in the first place, a certain number have their openings placed 

 horizontally or more or less reversed, and the walls of these are only 

 moistened by the aqueous vapor transpired from the inner surface of 

 the pitcher. In the pitchers that open upward there is but little water 

 found, even after a day's rain. Their office as ant drowners appears, 

 therefore, very problematic. Even the presence of the ants is not con- 

 stant, as we have already said. In contrast to those of Nepenthes they 

 are not arranged so as to retain the ants that may venture into them. 

 Finally, what seems to settle the matter is that in most cases we do 

 not find in them carcasses of drowned insects. 



To these direct objections we are tempted to add another of an indi- 

 rect character. Even granting that putrefaction might make soluble 

 the carcasses that fall in abundance into the pitcher, it is doubtful 

 whether the soluble products of that putrefaction would be directly 

 absorbed by the rootlets (the root absorption of all organic substances, 

 such as humic substances, being as yet one of the most controverted 

 and controvertible points in vegetable physiology). It would, on the 

 other hand, be highly improbable that the liquid fertilizer of the pitcher 

 could take on, during the life of that organ, the various nitrite-producing 

 fermentations whose products could be absorbed by the rootlets. This 

 objection, which ought to be presented a priori together with the facts 

 observed by Treub, convinces us that we ought to deny all carnivorous 

 function, either direct or indirect, to the pitchers of Dischidia. Their 

 true function is to aid the plant, which is of an epiphytic nature, to 

 struggle against transpiration, which is often excessive. The impercep- 



