148 



THE FACTORS 



[Part I 



and occupies only the upper half of the internode in which it occurs, 

 so that the principle of providing resistance to bending is no longer 

 applicable. 



Whether Humboldtia laurifolia belongs to the last-mentioned type or 

 to that of Triplaris, I must leave undecided. In this case numerous 

 bright red nectaries are present on the leaves and stipules. 



Cordia nodosa (Fig. 84), of which I was able to observe numerous 

 specimens growing wild at Pernambuco, belongs to still another type. 

 Here the long inferior internode of the flowering shoot, which in its 

 upper part forms a condensed tuft, bears, immediately below the leaves 

 and inflorescence, a lateral bladder into which a little pre-existing opening 



Fig. 84. Cordia nodosa. False whorl with inflorescence-axis and bladders. 

 One-half natural size. 



leads between the petioles. I found the bladder always occupied by 

 minute ants. Here the connexion between the dwelling-place of the 

 ants and the flowers is very clearly exhibited, and the same feature 

 is repeated in numerous other cases, for example in the lauraceous 

 Pleurothyrium macranthum, where only the axes of the inflorescence 

 are hollow and inhabited by ants. 



The famed myrmecophytes of the Malayan Archipelago, species of 

 Myrmecodia and Hydnophytum (Figs. 85 and 86), exhibit a type of 

 axial chamber quite different from the foregoing ones. Here it is no 

 longer a case of a single central chamber in a cylindrical woody internode, 

 but of numerous sponge-like communicating spaces in a succulent tuber, 

 which, since the plants in question are epiphytes, possibly in the first 

 place serve as a water-reservoir. The water is stored in the parenchyma 



