NUTRITION 385 



Saprophytes are very numerous and varied. They may be superfii ial, 

 or may penetrate the substratum thoroughly, showing finally at the sur- 

 face only the reproductive bodies. The very fact that they are getting 

 food from the 

 dead organism 

 indicates that 

 they are con- 

 suming it. In- 

 asmuch as they 



often must digest the food before it can enter their 

 bodies, they disintegrate the body on which they 

 feed. In the course of this digestion and disin- 

 tegration, many and varied chemical reactions 

 occur, some incited by the saprophyte, some in- 

 cidental to the changes it produces. These are 

 summed up for fluid media under the term fer- 

 mentation, and for solids under the terms decay or 

 putrefaction. Certainly in fermentation (p. 409), 

 and probably also in putrefaction and decay, some 

 of the most striking reactions are not connected \]k • 



with food getting, though apparently they are en- 



tire! v similar thereto. 



Organic debris. — It is not necessary that the If ' ','U'u 1 

 dead body retain any semblance of its original iljj rMjil 

 form. It may even be so far destroyed as to be m^ if Vh'j^| 

 mere particles of a soil; yet the saprophyte relies wL* *" U 

 on these for its food. Thus, the common mush- W \ $ 



room of comment' (Agaricus campestris) is grown \\| v 



upon a compost of soil and horse dung, the par- \l \ v<? 



daily digested remnants of grain and hay furnish- 

 ing the food for the mycelium. Indeed, every soil 

 containing organic matter supports a varied if piQ 6s6> _ Lea | of jy* 

 minute flora, whose operations are often indispen- penthes Mastersiatia.— Froma 

 sable to the welfare of larger plants. photograph by G.W.Ouver. 



Succession. — Nothing is more striking than the succession of sap- 

 rophytes that live upon a dead organism and finally dispose of all its 

 organic matter, each appropriating a suitable part and reducing that 

 to the most simple and stable compounds, until finally it " returns to the 

 dust whence it came." This emphasizes, too, the striking differences 



C. B. & C. HOT ANY — 25 



