BIOLOGIC RELATIONS BETWEEN PLANTS AND ANTS. 447 



upward, but there are also some that are horizontal, and others erect 

 with their closed extremities upward ; that is to say, preserving the 

 position they had during their formation. 



The pitchers of the Dischidias are often inhabited by ants. Beccari 

 has, for this reason, suggested that an irritation produced by insects 

 (perhaps by ants) may have caused the abnormal evolution of these 

 leaves that became transformed into pitchers. This deformation, in the 

 first place accidental, may have became hereditary by the "indefinite 

 and continual repetition of the phenomenon." Allow that the first 

 cause of this abnormal evolution was parasitism, which is a tenable 

 hypothesis, yet in the present condition of things there is nothing that 

 would lead us to ascribe to the punctures or bites of insects any part 

 in the formation of the pitchers. Whatever may be the part played by 

 ants in this formation we may yet inquire if any biologic relations 

 exist between them and the Dischidias whose pitchers they frequently 

 inhabit. Other insects rarely enter the pitchers. The ants found 

 there are always in good condition and generally in considerable num- 

 bers. The pitchers become true ant nests, sheltering some hundreds 

 of individuals and many larvas. The ants leave the pitcher with the 

 same ease that they 'enter it, for it possesses no arrangement for retain- 

 ing insects that have entered; on the contrary, the adventitious roots 

 that traverse it from the petiole to the bottom form, with their numer- 

 ous radicles, a sort of ladder leading to the outside of the flask. When 

 'we press a pitcher containing ants they leave it in great numbers, carry- 

 ing their larvae and their nymphae. It should be noted that the Dis- 

 chidias may, according to their situation, offer an asylum to ants, or 

 grow, independent of any relations with them, yet presenting absolutely 

 normal pitchers. 



We might suppose, on examining these curious plants, that they ought 

 to be classed as carnivorous, with Nepenthes and Cephalotus (Drude), 

 whose foliary pitchers or ascidia are regarded as veritable traps for 

 insects, capable of digesting their carcasses and absorbing the assimi- 

 lable products of such digestion. This is not the place to discuss vege- 

 table carnivorism, but it may be well to recall that in recent times the 

 supposed digestive function of these ascidia has been ascribed wholly 

 to the putrefactive bacteria that swarm in them as soon as they open 

 (at least in the case of Nepenthes). The absorption of the soluble prod- 

 ucts of this digestion or putrefaction has yet to be demonstrated. 



Wallich believed that the pitchers of Dischidia generally contain ants, 

 of which the greater number are drowned in the dirty liquid, appar- 

 ently rain water, that often half fills their cavity. Treub has shown 

 that this liquid is not an exudation from the pitcher (contrary to an 

 opinion advanced by Unger), its origin being wholly pluvial. 



Admitting that, in certain cases at least (for example, during the tor- 

 rential rains so frequent in the Tropics), ants may be drowned in the 

 nitcher, would their soluble products, derived irom the digestion, 



