442 BIOLOGIC RELATIONS BETWEEN PLANTS AND ANTS. 



transform nutritive principles in presence of the abundant free oxygen 

 brought to them by the active circulation of air in the cavities of the 

 tubercle. 



Beccari, on the contrary, is inclined to consider the eminences that 

 stud the galleries not as lenticels, but as organs of absorption analogous 

 to those of moisture-loving plants (Corallorhiza, JEpipogium, TriuNs, 

 etc.). It may be remarked that certain terrestrial parasites, such as the 

 Balauophorene, possess, on their parts that come in contact with the 

 soil, organs quite similar in appearance to the lenticels. It is with these 

 apparently absorbent organs that Beccari correlates the internal emi- 

 nences of the galleries. If this supposition is correct, the interior of the 

 galleries bristles with true internal roots. 



The figure given by Treub of these lenticels in course of formation 

 reminds one of the formation of a callus upon the cut surface of a cat- 

 ting. The conditions that determine the formation of this callus — dark- 

 ness, moistnre, heat, a nutritive environment — are realized in the gal- 

 leries of the Myrmecodia. The functions of the callus of a cutting are 

 perhaps absorbent. A cutting upon which a callus is formed is sure to 

 "take," which is about the same thing as saying that the absorption of 

 nutritive substances is assured. Certain of these supposed lenticels 

 may be transformed into real adventitious roots, which seems to con- 

 firm the theory that their function is absorbent. In spite of the great 

 quantity of nutritive matters they contain, the lenticels are never 

 gnawed by ants. There is therefore no reason to consider them as food 

 bodies. These lenticels can not in any case act the part of organs that 

 secrete digestive ferments. Their absorbent power for nutritive sub- 

 stances brought from without is still doubtful. 



One point remains established. The ants penetrate the tubercle of 

 the Myrmecodia and live there because they find an assured shelter. 

 But it would be going too far to say that they render no service to the 

 plant on which they lodge. The circulation of air in the galleries of 

 the tubercle is probably indispensable, and the presence of a flocculent 

 tissue there is well calculated to impede circulation. Perhaps the ants 

 tree the young galleries from the flocculent mass of dried cells. This 

 would be a case of mutualism quite analogous to that of certain acarids 

 known to install themselves upon the fur of mammals and the down of 

 birds for the juirpose of removing epidermic debiis that incumbers 

 their hairs and feathers. The ants, like the acarids, act the part of 

 scavengers. 



There seems to be no doubt but that ants may form an army of 

 defenders useful to the plant in case it is attacked by plant-eating 

 animals. It is an established fact that if a tubercle inhabited by the 

 ants is struck, even slightly, thousands are seen to emerge and swarm 

 on the surface, reentering their domicile as soon as the danger is past. 

 But this has not been demonstrated upon plants in their natural wilds. 



The part played by ants in fertilization is doubtful. The Myrmecodias 



