I4<5 



THE FACTORS 



[Part 



differs neither externally, nor in the nature of the tissues lying with 

 it, from the groove of which it forms the upper extremity. In spi 

 of the absence of a protective army, the ant-free Cecropia proved 

 be quite uninjured, apparently because the waxy coating of the ste 

 prevented the leaf-cutting ants from climbing. It has indeed been provi' 

 experimentally that a waxy coating offers an insuperable obstacle \ 



Cecropia adenopus, which probably mcl 



of the other species of the genus resemb 



represents a higher stage of adaptation th; 



Acacia cornigera and A. sphaerocephala, f 



it exhibits as adaptations not only the foo 



bodies, but also the spot that is prepar 



beforehand to be bored through. In the latl 



respect Clerodendron fistulosum, discovered 



Beccari in Borneo, resembles Cecropia. Otl 



species however have gone a step further, |- 



they have succeeded in forming an openi 



through the wall of the hollow internoi 



The causes that lead to the formation of i 



opening have not yet been explained ; i 



certain cases it may be the result of a tensia 



in others perhaps due to the death of tl; 



tissues of a circumscribed area. The openi 



is sometimes narrow, like a slit, so thatt 



has to be widened by the ants, as in Duni 



hirsuta, according to Schumann ; sometirrs 



from the first it is more circular and poreli , 



and thus perfectly fitted for its subsequent i; 



(Fig. S3, 1-3). 



The spontaneous appearance of an open ; 

 in the previously intact wall of hollow int- 

 nodes was first rendered probable by Bo\r 

 in the case of Humboldtia laurifolia, th 

 by Schumann in several species. I fit 

 became fully convinced of its truth in e 

 botanic garden at Buitenzorg, where I (- 

 served quite free from ants specimens ''f 

 Humboldtia laurifolia and Triplaris americana, also Ficus inaequal' . 

 hitherto unknown as a mj-rmecophyte, all with a well-differentia i 

 entrance-aperture at the upper end of most, or of all the internodes. 



' Schimper, op. cit. p. 66. 



' But proof is still wanting that it is inhabited by ants in its native habitat. In ' 

 Singapore botanic garden most of the specimens were inhabited. 



Fig. 82. Cecropia sp. of the 

 Corcovado Mountains, near Rio de 

 Janeiro. Part of the myrmccophilous 

 stem. Natural size. 



