P4 PRINCIPLES OF GARDENING. [CH. II. 



this, oxygen must be absorbed, and the extra pro- 

 portions of carbon be got rid of, as is evident from the 

 following table of constituents : — 



100.00 100.00 100.0 



That such processes actually do occur, Saussure 

 has demonstrated by experiment : he fomid that 

 moist wood, exposed to the air, absorbed oxygen, 

 evolved carbonic acid, and water was evidently de- 

 composed. Thus, then, putrefaction seems to render 

 organic matters fit for the nourishment of plants, by 

 converting them into saccharine and mucilaginous 

 compounds, capable of solution in water. Hence 

 the phenomenon of wood, which is slow of decom- 

 position, being a permanent manure ; animal matters 

 which rapidly putrify, being transient, though tempo- 

 rarily powerful : hence the economy of using partially 

 decomposed composts is also rationalized ; when com- 

 pletely decomposed, their soluble matters, being more 

 than can be consumed at the time by the crop, pass 

 away with the drainage water, much is lost in the 

 state of gas, and all that is left, are a few earthy. 



