GEEGAEIOUSNESS AITD SOCIABIIITT OF SPECIES. 107 



(t) In most parts of India propter, the teik is characterised by- 

 tardy and difficult germination, the seed either requiring to lie in 

 the ground for at least a whole year exposed tcl weather influences 

 and other causes of destructioh, or sprouting too late in the rainy 

 season to be strong enough to survive through the following 

 dry season or to escape strangulation by the heavy gtowth of 

 weeds and other vegetation already on the grbuhd. 



(m) The seed is the common food of iriaiiy- rodents, parrbts, &c. 



(n) The young plartt is extteniely seiisitive to frost. 



(o) The upper portion of the taproot of the seedUng is greedily 

 devoured by rats. 



(p) Some birds, as the bush-qiiail, peck off the cotylfedonary 

 leaves and the terminal bud, as soon as these appear. 



Prosopis spicigera. 



This species, thanks to the enormous length of taproot (60 feet 

 and upwards) it can develop, is pecuUarly a tree of very dry re- 

 gions and ceases where the rainfall exceeds 40 inches. In the 

 Punjab and Eajputana, with a rainfall varying from 12 to 25 inches, 

 it is gregarious on high ground where, the depth of the stratum of 

 permanent moisture being very far below the surface of the soil 

 and the subsoil being strongly saKne or consisting of shingle and 

 boulder beds, no other trees or even large shrubs can grow. De- 

 scending towards the main drainage channels it is obliged to yield 

 a less or greater portion of the ground to other trees. In Sihdh, 

 where the rainfall is less than 10 inches, the pure Prosopis forest 

 approaches much nearer to the streams, but still remains above the 

 level of inundations, In Bundelkhand and from the Narbada 

 southwards, and in the proximity of rivers elsewhere, the tree is 

 no longer gregarious, the greatly diminished distance, below the 

 surface, of soil sufficiently moist for vegetation enabling other 

 species to grow side by side with the Prosopis, and in many, if not 

 in most, cases even to preponderate over it, thanks to their larger 

 stature, their greater shade-enduring capacity, their superior hard- 

 ihood in those comparatively moist soils in respect of frost, the 

 rocky subsoil, and some other characters which vary with the re- 

 gion and the locality. 



Concluding Remarks. 



We need not add to the preceding instances to prove that the 

 gregariousness or sociability of a species is purely the outcome of 



