280 PROCESSES OF DECAY. 



a spirit lamp flame or Bunsen burner. When all moisture 

 has evaporated, cool and note the black residue. This is 

 carbon. 



From what source did the toadstool obtain the carbon ? 

 From the atmosphere ? No, because these plants do not 

 have any green colouring matter, without which carbon 

 cannot be obtained from the air by plants. From the 

 soil ? Yes, from dead vegetation chiefly. Eventually the 

 great bulk of the toadstool becomes subject to bacterial 

 forces, but some of it lives as spores, which scattered by 

 the wind and other agents sporulate upon other dead 

 vegetation, and thus continues the work of disintegration. 



In conclusion these lessons should be summarised thus : 

 Note the circulation of matter. 



Soil and air constituents are built into the bodies of 

 plants. Plants decay or animals feed on them: event- 

 ually animals decay. In decay plants and animals are 

 decomposed and disintegrated into the compounds carbon 

 dioxide, water, ammonia, etc. These again are made use 

 of by living plants and the cycle is re-commenced. Were 

 decomposition not to take place a time would eventually 

 come "when all the carbon and nitrogen would be im- 

 prisoned in dead plants. Thereupon all life would cease, 

 and the whole earth would be one great bed of corpses " 

 (Kerner) . Beneficent bacteria ! 



