SO THE STBUGGLE FOB EXISTENCE. 



nurse, and which will drive it out, or at least predominate over it, 

 when they no longer require its protection. 



The number of flushes of new leaves that a species brings out 

 during the year is also an important factor for consideration. 

 Every new flush of leaves is, thanks to the large accumulated store 

 of reserve materials, accompanied with a sudden outburst of both 

 lateral and upward extension, during which the tree is able to push 

 up against and through obstacles against which it may at other 

 times be completely powerless* The Hardwickia produces at least 

 two such flushes every year, and hence its ability to beat species 

 much more shade-enduring than itself. Thus where it grows with 

 khair, it is common to see young Hardwickia seedlings and sap- 

 lings gradually making their way up through the close crowns of 

 poles and trees of that species. The khair being leafless in April, 

 when the Hardwickia brings out its first and strongest flush of 

 leaves, overtopped individuals of this species are able to push up 

 then, without any impediment, into and through the overhanging 

 crowns of the khair. Then, when towards the end of the hot weather 

 or at the beginning of the rains, the khair puts forth new foliage, 

 they may of course be again overshadowed ; but they do not remain 

 so long enough to suffer in health or vigour, and yet long enough 

 for the new shoots produced at this second flush to remain suffi- 

 ciently herbaceous to form long internodes, a circumstance that only 

 makes them push up all the faster. 



Wo may also quote here the instance of associated sal and Termi- 

 nalia tomentosa. The latter species is very much more shade-endur- 

 ing and broader-crowned ; nevertheless, when the two grow close 

 together, the sal, owing to its remaining in leaf longer and coming 

 into leaf again earlier, and also to its putting forth more than one 

 flush during a single season, can go up straight and force in the 

 crown of its neighbour. 



Lastly, where late frosts occur, trees that bring out new leaves 

 early in the year will naturally suffer more than others whose 

 foliage-buds being to swell up, preliminary to bursting forth, only 

 after the frosts are past. Abies dumosa suffers in this manner ; and 

 thus also is explained the impossibility of acclimatising deodar and 

 the Indian silver fir in Northern Europe. 



XVII. A CLIMBING HABIT. Under Condition III (r/) we have 

 explained how climbers, considered as an extraneous accident in 

 a forest crop, kill or at least weaken trees, and thus assist neighbour- 

 ing trees in gaining the victory in the struggle for existence. In 

 this place, on the contrary, we are concerned with the struggle be- 



