84 THE STKT7GGLK FOE EIISTENCE. 



folia in most cases, &c.; or it maybe exclusive without being tenaci- 

 ous, as, for instance, sissu at Changa Manga, where without watering 

 and special care that species would entirely disappear ; or it may 

 be both tenacious and exclusive, like sal, Anogeisms- pendula, many 

 bamboos, Ougeinia dalhergioides, Quercus semecarpifolia and incana, 

 deodar, silver fir, sissu in its proper station, &c. As long as the 

 soil and climate do not keep out other species, mere tenacity alone- 

 will not suffice to enable a species to predominate : it must be ex- 

 clusive as well. 



The conclusion to be drawn is obvious. If our object is to raise 

 mixed crops, we may be certain that, as a general rule, we cannot 

 secure a favourable and permanent mixture by having them of uni- 

 form age throughout. 



For further observations connected with this subject the student 

 is referred to the " General Remarks" under the .Fourth Case oa 

 page 93. 



Examples, of the Third Case^ 



Instances of this Case are furnished by many mixed khair and 

 sissu forests, mixed tamarisk, Populus euphratica and babul forests, 

 copses in which no standards are left, &c. Artificially raised 

 forests coming under this head are extremely rare in India, if they 

 exist at all. 



SECTION lY. 



FOURTH CASE.— Mixed crop composed of individuals 

 of aU ages. 



We have already seen that in a mixed crop consisting of trees 

 of one and the same age, the consideration of the circumstances 

 which decide the struggle for existence is extremely compUcated, 

 and that none of them can be examined apart without having to take 

 into account the effects of some other or others. Under the pre- 

 sent head we have one more cause of complication, viz, the exis- 

 tence ot various ages. This circumstance influences more or less 

 the working of nearly all the rest, and the best plan to follow 

 would, therefore, seem to be to repeat here, in their due order, 

 the various headings of the preceding Cases, and consider under 

 each what qualifying effect it produces. Hence in what follows it 

 must be understood that, in the absence of any qualification, what- 

 ever has been said under those Cases holds absolutely true also in 

 the present one. 



