46 THE STRUGGLE FOB EXISTENCE. 



latitude, distance from the sea, aspect, altitude, configuration of the 

 earth's surface, clearness of the atmosphere, &c. ; so that while it 

 may succumb in one place, it may hold its own in another, and 

 even conquer in a third, its rivals being in all three places the same. 

 Thus in southern latitudes Anogelssus latifolia is a very strong spe- 

 cies in low situations, on level ground, on northerly aspects and 

 even at the bottom of valleys, while in Northern India it is con- 

 fined chiefly to southerly slopes and comparatively high elevations* 

 Again, young sal in the Nandaor valley in Eastern Kumaon is re- 

 markably more shade-enduring on southerly than on northerly 

 slopes. When the season of vegetation is very short, as at very 

 high altitudes, all species become extremely light-demanding and 

 the forest growth at those elevations is always very open. The 

 more rapidly a species completes its annual quantum of growth, 

 that is to say, the greater its vigour of assimilation is, the better is 

 it adapted to compete successfully with other species equally or 

 more shade-enduring : e. g., the teak, which in many parts of 

 Central India develops its entire annual shoot in three months ; the 

 bamboos, culms of which attain their full length in a few weeks ; 

 and so on. 



Species become more shade-enduring also with increasing humi- 

 dity and richness of the soil within the limits special to each. The 

 reason of this is of course the fact that the more favourable a soil 

 is, the more vigorously will plants nourished in it assimilate ; and 

 the result is manifest by an increasing fulness of crown which 

 completely changes the habit of the species in question. Thus 

 Terminalia tomentosa, Bombax malabaricum, &c., present quite dif- 

 ferent aspects in Northern, Central and Southern India. Trees 

 grow noticeably closer together on low river banks and on nor- 

 therly slopes. The effect just indicated is irrespective of the fact 

 that in good soil plants can feed within less space and, therefore, 

 have a more restricted ramification of roots. 



The remarks in the preceding paragraphs should be read in 

 connection with what has been said under Condition IV in the first 

 two Cases. 



The shape of the crown also exercises a considerable influence 

 on the struggle for existence. Sal, with its long narrow crown, is 

 able to push up through any small gap it may find in the leaf- 

 canopy above it. The long tapering crown of the deodar adds 

 very considerably to its ability to grow up under cover. Shade- 

 enduring trees will at once spread out a branch here and a branch 

 there iiito the smallest openings through which h'o-ht enters. Of 



