io6 THE NEW AGRICULTURE. 



blood circulates within the veins of man, certainly effects cer- 

 tain chemical changes, but these are constructive rather than 

 destructive, and are concerned with the re-formation, trans- 

 portation and deposition of elements which were broken down 

 and decomposed before they had found entrance to the interior 

 at all. 



The "vital activity" of a plant is a term not clearly denned, 

 but is meant to convey the idea of a subtle power possessed by 

 the rootlets by which they appropriate from the soil these ele- 

 ments which are necessary to the plant's wellbeing. Just 

 how "vital activity" operates in this regard we do not at pres- 

 ent know. That it is much concerned in the appropriation 

 of food there can be no doubt, but it does not seem at all likely 

 that it has much part in the preparation of the raw material 

 by which it is rendered fit for ingestion. 



The matter of practical importance, and therefore of the 

 highest interest, is the established fact that the prime factor 

 in soil fertilization is the presence and activity of soil bacteria. 



The composite elements of a plant are carbon, hydrogen, 

 oxygen and nitrogen ; and, in smaller measure, potassium, lime, 

 magnesium and phosphoric acid. These last elements are 

 usually abundantly present in almost all soils. If they seem 

 to be lacking it is not that they are really so, but that they are 

 locked in combinations which render them unavailable. By 

 methods and systems of plowing and planting these elements 

 may be unlocked and brought out into useful form, so that 

 no soil need be permanently poor for the lack of them. As 

 for the carbon, hydrogen and oxygen, they are all supplied 

 by the water and by the air. 



It is nitrogen, therefore, that the farmer is most solicitous 

 to supply. It is for this that he accumulates stall manures 



