CHAPTER III 



REPRODUCTION. CONSTITUENTS AND HABITS 



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Structurally a fungus consists of a cell or cells made up of semi- 

 fluid protoplasm surrounded by a thin wall of cellulose."^' The cell 

 may be spherical, oval or elongate, or is commonly united with 

 others into a thread-like structure known as a hypha. Many 

 hyphae, more or less entangled, form what is known as mycelium, 

 which may be cobwebby or flocculent or spread out in an irregu- 

 lar compact layer. Most hyphae are formed of many cells by 

 the division of the original cell and the formation of septa or cross 

 partitions. In certain cases no septa are formed and the boundary 

 between the cells is obscure, in which case we have a coenocyte ; 

 this concUtion facilitates the rapid transfer of food material from 

 one place to another. The hyphae may be simple or branched, 

 and as in higher plants the branching may be monopodial or 

 dichotomous. True roots are never produced but frequently 

 root-like structures are developed as hold-fasts to anchor the 

 plant to the substratum on which it grows. 



In parasitic forms, irregular tubercular or root-like projections 

 are developed which sometimes penetrate the cell walls of their 

 host, for the purpose of absorbing the nutriment that would other- 

 wise serve as food for the host plant itself ; these are calleci haus- 

 toria. Hyphae are sometimes united to form cord-like structures 

 known as mycelial strands and often become matted together 

 into a felt-like mass or are sometimes hardened into a corky, 

 horny or even woody structure to serve as a protection to more 

 delicate exposed parts, particularly in forms that are perennial in 

 their habits. 



Reproduction is accomplished in various ways. In unicellular 

 forms it takes place by budding (gemmation) as in the yeast 

 plant, by self-division (fission) as in bacteria, or by free cell for- 



*This fungus cellulose apparently differs slightly from normal 

 cellulose, yielding less readily to standard tests than the cellulose of 

 green plants. 



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