CHAPTER XXV 

 THALLOPHYTES (Continued)— FUNGI 



The fungi are very similar to the algse in structure and 

 methods of reproduction, biit since they do not possess chloro- 

 phyll they are very different physiologically; that "is, the;v are 

 unable to manufacture their own food and, like the animals, must 

 depend upon the green or chlorophyll-bearing plants. They 

 range from the extremely small, unicellular, microscopic forms to 

 the very large fleshy forms. They may be divided on basis of 

 habit into- parasites and saprophytes; the parasitic species feed- 

 ing on living plants or animals, vs^hile the saprophytic species live 

 on decaying organic matter. Their strong resemblance to the 

 alg-ffi indicates that they are probably the dracendants of tiie 

 algse. In fact, it is a true case of retrogressive evolution. Many 

 of them are the causes of diseases of plants and some of them are 

 very destructive tO' our farm crops and natural forests and the 

 cause of very heavy losses. We have already called attention 

 to the five most important divisions (page 260) : Myxomycetes, 

 Schizomycetes, Phy corny cetes, Ascomycetes and Basidiomycetes. 

 The last three may be considered the true fungi. There is still 

 another — the fungi imperfecti — including a very large number 

 of species, of vifhich the life history is not definitely known or 

 which do not coincide with the other divisions. 



Myxomycetes or Mycetozoa. — This group of organisins is 

 commonly known as " slime molds " and possesses characters of 

 both plants and animals (Fig. 124). The plant body is a naked 

 mass of protoplasm known as a plasniodium. It travels very 

 slowly by a creeping motion and lives very much like a large 

 amoeba (very simple form of animal life) by means of stream- 

 ing projections of the protoplasm. It pushes over and encloses 

 many small organisms, which it digests. 



18 273 



