ROOT. 15 



roots have no means of finding their way into 

 the earth on the outside of the house. 



The spongioles and newly formed parts of 

 the root contain considerable nitrogen, a sup- 

 ply of this gas therefore seems necessary to 

 their health. Manure which contains nitrogen 

 in abundance must therefore be of consequence 

 to them. It has lately been asserted that those 

 seeds which contain most nitrogen vegetate the 

 earliest. 



It is supposed by some that the introduction 

 of oxygen into their system is as indispensable 

 to them as to animals. 



It seems more probable that the^ oxygen of 

 the atmosphere, combining with a certain quan- 

 tity of carbon, forms carbonic acid, which they 

 absorb and feed upon. 



It is at least certain that the exclusion of air 

 from the roots will always induce an unhealthy 

 condition, or even death itself. This may be 

 one of the reasons why stiff, clayey, tenacious 

 soils are so seldom suited to the purposes of the 

 cultivator, until their adhesiveness has been 

 destroyed by the addition of other matter, such 

 as sand or manure. 



After the juices have circulated through a 

 plant and performed their destined offices, what 



