322 STRUCTURE AND LIFE HISTORIES 



things plants or animals. Not being able to manu- 

 facture their own food, they must find it ready made. 



SAPROPHYTISM 



302. Decay. Perhaps the simplest case of the nutrition 

 of non-green plants is the absorption of food from the 

 organic remains of other plants or of animals. When 

 the spores or other reproductive bodies of such plants 

 begin to grow upon such a substratum, they secrete 

 various enzymes which begin to disintegrate it, reducing 

 it to simpler, soluble substances. This is the process 

 commonly known as " decay," and the plants which 

 cause it are called saprophytes. 1 The word "decay" 

 is derived from a Latin word, decidere, which means 

 to fall apart, in allusion to the fact that the decaying 

 substance is being disintegrated or broken down into 

 simpler substances, which are recombined by assim- 

 ilation, in the cells of the saprophyte, into protoplasm 

 like its own. Such a state of existence is called sapro- 

 phytism. 



303. Fungus -saprophytes. Among the more familiar 

 saprophytic plants may be mentioned the common bread- 

 mold, the fungi that are instrumental in ripening cheese, 

 the so-called " mildews," which often grow on old moist 

 pieces of leather, and numerous other filamentous fungi; 

 the bacteria which cause the decay of meat and other 

 substances, bacteria which cause the retting of flax stems, 

 thus freeing the bast fibers from which linen is made by 

 causing the decay or rotting away of the remainder of 

 the tissue, the bacteria which convert cabbage leaves 



1 From the Greek words sapros, rotten + phyton, plant. 



