12 VEGETABLE GABDENING. 



form in which they become available to the crops. 

 It is well to remember that all decay is the result of 

 the vital activities of bacteria and fungi. If these 

 did not exist there would be practically no decay 

 and the earth would be cumbered with the dead 

 remains of pre-existing forms, and long ere this all 

 the available material would have been locked up. 

 No new living things could have been formed. The 

 bacteria and their allies come between the dead and 

 the living, and enable material to be used over and 

 over again, thus ensuring that the death and decay 

 of what is gone should give the means of life to what 

 exists. They perform a large and far-reaching share 

 in converting the soil into nature's great storehouse 

 of food to meet the wants of the world. 



It is not possible here to follow up the subject in 

 detail, but only to state briefly that the main place 

 of bacteria in the economy of nature is to break down 

 the complex compounds of animal and vegetable 

 materials through an infinite number of changes, 

 finally into such simple things as carbonic acid, 

 water, ammonia, and free nitrogen. Speaking gen- 

 erally, the greater the amount of humus present in 

 the soil the greater the number of bacteria ; a rich 

 garden soil contains very large numbers. 



Bacteria are present in the greatest numbers a few 

 inches below the surface. The surface soil itself is 

 often too dry for their increase. Deep down there 

 is too little food or too little air. But at a depth of 

 about 4 to 9 inches they may be found at the rate 

 of several millions in each ounce of soil, to state only 

 a low estimate in general terms. 



These facts should be kept in mind in all soil opera- 



