108 PLANT LIFE 



on the development of a correspondingly 

 thick trunk. 



But the various exigencies and risks in- 

 separable from a climbing habit, have given 

 free scope to the play of individual variation 

 among the numerous species, both related 

 and unrelated to each other, of which the 

 great group of the climbers is composed. 

 It is this circumstance that gives them their 

 special interest, and also renders them so 

 instructive. 



Many of the climbers which grow in the 

 tropical jungles exhibit extreme specialisation 

 in connection with their climbing habits, by 

 which they are enabled rapidly to reach the 

 leafy canopy of the forest, although this is 

 often many feet above the ground. Some- 

 times they steal a march on circumstances, as 

 it were, and the seed is able to germinate in 

 the upper fork of a tree. This occurs in 

 many of the large figs, e. g. the India-rubber 

 Fig, which, perhaps, can hardly be called 

 a climber in the ordinary sense of the term. 

 Plants of this kind produce roots which 

 rapidly grow downwards and penetrate the 

 soil, the young fig securing the great ad- 

 vantage that, when its foliage sprouts forth, 

 it is very soon fully exposed to light. 



Other climbers behave differently, and 

 more nearly resemble the kind of growth of 

 an ordinary plant, but with certain significant 

 differences. The seed germinates on the 

 ground, and the thin shoot, which grows 



