rive at the great object of our inquiry What is the planter 

 to do to rid his trees of these pests ? All outward applica- 

 tions must be considered as useless, first because of the 

 labor of applying them, and the chance indeed the certainly 

 of their being washed off in the rains, and secondly as 

 their effect could only temporarily affect the condition of 

 the plant. 



Agricultural chemistry distinctly tells us that the 

 process of decomposition of vegetable matter in the soil is 

 not only gradual, but that before ultimate decomposition can 

 be effected the substance has to pass through various phases 

 and that peculiar mechanical conditions of the soil either 

 accelerate or retard the process and that indeed under 

 certain circumstances such may be completely checked, and 

 that certain products may accumulate to such an abnormal 

 extent as to prove positively pernicious. Liebeg comments 

 at great length on the technical difference of fermentation, 

 putrescence, and decomposition and explains the various 

 phases that matter passes through during such processes. 

 Professor Anderson says, " at one peculiar stage of the pro- 

 cess of disintegration vegetable matter is converted into 

 either^ Humin or Ulmin, both, of which ar insoluble in 

 alkalies, that further on, the products become soluble in 

 alkalies, and contain humic, ulmic and geic acid, and finally 

 by a continuance of the wonderfui process, crenic and apo- 

 crenic acids are produced." The accumulation of Humus in 

 any soil may be favored by many circumstances among 

 which must be conspicuous faulty mechanical condition and 

 the exhaustion of the mineral constituents. After a soil has 

 been long superficially worked, as we found before, it lose 

 its granular form and becomes clogged ; vegetable matter 

 contained in, or buried in such a soil, is hermetically sealed 

 against the entry of OXYGEN, and consequently the decom- 

 position of the substance is materially impeded and if other 



