90 *HE STRUGGLE FOR EXISTENCE. 



species bettvt scnpted to the climate mitigates its excessiveness for 

 associated species that are less at home, thereby enabling such 

 species to thrive better than they could otherwise do. 



XI. GRADIENT. -One of the effects of gradient being rapid and 

 effective drainage, it follows that on slopes with a naturally dry 

 soil young plants, to whatever species they may belong, will be safer 

 against drought when growing with larger individuals, especially if 

 all or most of these possess a powerful root-system, a condition that 

 is more likely to be realised if there are several species present. 

 Under the same circumstances the young plants will also be better 

 protected against erosion and against damage by snow. Moreover, 

 the neighbourhood of large trees of various species, all of which 

 would seldom be out of leaf at one and the same time, would neces- 

 sarily prevent excessive insolation on slopes receiving the sun's rays 

 more or less perpendicularly, and also mitigate the severe after- 

 effects of frost on steep easterly and southerly slopes. 



XII. SEEDING. Under the Third Case this Condition was con- 

 sidered under seven main subheads. Here we can obviously make 

 additional remarks only under the first, second, fourth, fifth and 

 seventh of these subheads, viz. the relative abundance and frequency 

 of seeding, the season of fall and the relative vitality and germin- 

 ative power of the seeds, and the relative age at which fertility is 

 attained. 



(a) Relative abundance. A tree becomes fertile long before it 

 has attained its full height and spread of crown, and it remains so 

 up to the moment of its natural death. The quantity of seed pro- 

 duced, being in proportion to the size of the crown, increases with 

 the age of the tree until decline sets in, when it gradually dimin- 

 ishes as the crown contracts and becomes more and more spare from 

 year to year. With individuals of different ages distributed pro- 

 miscuously throughout the crop, at nearly every point will be 

 found a tree of one species or another in more or less full bearing. 

 Every species is hence certain to be represented by at least a few 

 fertile individuals by which it can be perpetuated in the crop, and 

 a permanent mixture of the majority, if not all, of them is thereby 

 assured. 



(1>) Relative frequency. In the case of species which seed in a 

 general manner only at intervals of two or more years, it is not 

 uncommon to find some individuals here and there seeding within 



O 



that interval. Thus even some bamboos, e.g. Dendrocalamus strictus, 

 flower sporadically every year. In Nimar, in the Central Provin- 

 ces, Hardwickia binata flowered gregariously ia 1873, not at all in 



