CHAPTER V 



CHARACTERISTICS OF THE TRUE FUNGI 



CLASS III. EUMYCETES 



The true fungi or hyphomycetes {iKpri, a web + yuu/cTjs, a mushroom; 

 are thallophytes in which the thallus, as the Greek derivation implies 

 consists of a system of threads {kyphm) which form a cobwebby struc- 

 ture known as the mycelium (Eig. ii). A single thread of the myceliurr 

 is an hypha (plural hyphae) and a hypha may be unicellular, or multi- 

 cellular. All true fungi are colorless, that is they are chlorophylless 

 and although they may have other pigments present, yet in the absence ol 



chlorophyll, they are dependent plants 

 As dependent plants, they must gel 

 their organic food from extraneous 

 sources, and as all organic matter is 

 either dead, or living, a natural classi- 

 fication of fungi into saprophytes anci 

 parasites can be made. A saprophyte 

 (craTrpos, rotten + <j)vt6v, a plant) is an\ 

 organism which derives its chief foo( 

 supply from dead, or dead and decayinj.' 

 animal or plant organic material, while 

 a parasite (irapdo-tToj, one who lives at another's expense) is an 

 organism, which exists at the expense of living animals, or plants 

 (Fig. 12). But some saprophytes may change their mode of nutri- 

 tion and become parasitic; such saprophytes are called facultativt 

 parasites, while those which retain their saprophytism under all condi 

 tions are obligate saprophytes. Again some parasites can adjust theii 

 methods of nutrition, so that they can become saprophytes. Sucl 

 parasites are called facultative saprophytes, while those organism- 

 which are always parasitic are obligate parasites. These distinctions 

 are useful, but it should be emphasized that there is no absolute border- 

 line between one condition and the other. There are imperceptibli 



42 



Fig. II. — Gray mould, Mucor, 

 showing mycelium and the sporan- 

 gia on upright sporangiophores. 

 {After Conn.) 



