130 COMPOSITION OF rOBEST CBOPS. 



(2) When a shade-avoiding species has to be cultivated side by 

 side with a more rapidly growing and particularly dense-crowned 

 species, there is similarly no alternative. 



(3) Certain individuals, generally of the most valuable species, 

 are sometimes preserved, when the rest of the crop is felled, in or- 

 der to allow them to acquire larger dimensions. These must in- 

 evitably inflict some injury, by the cover of their crowns, on the 

 succeeding new generation, But the mischief can evidently be 

 minimised by selecting them st3,nding in groups pf gre9,ter or les3 

 extent. 



SECTION III. 

 Characteristics of an auxiliary species. 



The meaning of the expression "auxiliary species" has been al- 

 ready explained in Definition 51 on page 7, But after what has 

 been considered in the foregoing sections, we are now in a position 

 to lay down more strictly the full connotation of that term. 



An auxiliary species mu^t fulfil the following essential condi- 

 tions;-^ 



1. Ji must become readily marketable as soon as it has reached 

 the pole stage. — Until this stage of growth has been attained, every 

 individual tree and shrub in a crop, by its struggle for existence 

 with its neighbours, contributes towards the favourable develop- 

 ment of the crop,- 'TChenceforth a tree here and a tree there begins 

 to hamper the free growth of, or threatens to suppress, others more 

 yalusble than itself and must, therefore, be removed at once. Un- 



. less the stems so rejnoved are collectively readily marketable, and 

 their sale-value is at least aufficient to cover cost of felHng and ex- 

 port, it is evident th9,t the unproductive nature of the operation in 

 question would, in the majority of instances, prohibit its ever be- 

 ing undertaken at the right moment, 



2. It must be a soil-improver. — This condition is obvious, if the 

 other species in the crop are shade-avoiding, and, therefore, spare- 

 crowned ; and it is equally obvious that, if these latter species are 

 shade-enduring and hence dense-crowned, their auxiliary must, 

 unless it is ultimately to be completely driven out of the crop, also 

 be dense-crowned, and thus necessarily a soil-improver. 



3. As a consequence of the immediately preceding condition, it 

 must also be shade-enduring. — To be dense-crowned is to be shade-i 

 enduring. 



