20 HOW CROPS FEED. 
out which no life is possible, is largely influenced. Water, 
whose excess or deticviency is as pernicious as its proper 
quantity is beneficial to crops, enters the plant almost 
exclusively through its roots, and hence those qualities 
of the soil which are most favorable to a due supply of 
this liquid demand careful attention. The absorbent pow- 
er of soils for the elements of fertilizers is a subject which 
is treated of with considerable fullness, as it deserves. 
Our book naturally falls into two divisions, the first of 
which is devoted to a discussion of the Relations of the 
Atmosphere to Vegetation, the second being a treatise on 
the Soil. 
