156 Coffee Planting. 



to go on bearing a crop of 3 or 4 cwts. per acre 

 every year till doomsday. The question then 

 arises, which of the two cases is the more desirable ? 



A consideration of by no means trivial importance, 

 also, is that the cost of weeding will be much smaller 

 under shade than in open clearings. 



Now comes the question as to the description 

 of shade to be provided. It is a well-known fact 

 that certain trees exercise a prejudicial influence on 

 particular plants in their neighbourhood, while seem- 

 ing actually to benefit others. This is probably 

 due in part to the excretion given off by the roots 

 (by a process perhaps similar to that which prevails 

 in the animal kingdom), and which, while actually 

 useful as manure to one description of plant, may be 

 no less noxious to another. Again, some trees, 

 instead of delving down for their sustenance into 

 the sub-soil, prefer spreading their roots abroad 

 near the surface, and thus abstract nourishment and 

 moisture which cannot be spared them. Some 

 trees also exhale gases injurious to other vegetation. 

 This is the case in a marked degree with the elder, 

 the walnut, and the laburnum of Europe ; and 

 with the orange, lemon, citron, &c., of the tropics. 

 All these points have of course to be considered. 



I am strongly in favour of the Jack as the 

 tree best suited for providing shade for fields of 

 coffee. In the first place, its presence, so far from 



