FUNGUS-FLOEA. 



INTRODUCTIOX. 



Nature axd Origin of Fosgi. 



In a systematic work the very fascinating study of ftmgi, 

 comprising general morphology, life-histoiy, etc., can receive 

 but very brief attention ; nevertheless, a clear knowledge of 

 such is indispensable to an intelligible appreciation of 

 systematic work, -which, if based on the system of natural 

 affinities, is the outcome of a correct knowledge of the 

 morphological and physiological peculiarities of the members 

 under consideration. 



Fungi belong to the division of plants known as Crypto- 

 gams, amongst which they are conspicuous by the entire 

 absence of chlorophyll. This peculiarity determines the mode 

 of life of the fungi, and limits their distribution to those 

 places where organic matter is present, which serves as 

 food, as owing to the absence of chlorophyll inorganic 

 matter cannot be assimilated. Those fungi that feed on 

 dead organic substances, as decaying wood, vegetable humus, 

 &c., are called saprophytes : whereas those that derive their 

 food from living pl^ts or animals are known as parasites. 

 Some species are saprophytes during one period of their 

 existence and parasites at another. 



Fungi are not the only Cryptogams devoid of chlorophyll ; 

 two other groups, the Mjrxomycetes or Mycetozoa, and the 

 Schizomycetes or Bacteria agree in this point, but these 

 latter are distinguished by the absence of hyphae or my- 

 celium. The tissues of ftmgi always consist of rows of cells, 

 called hyphae; these may consist of very long continuous 

 cells witiiout transverse septa, or septa may be present, when 



VOL. I. B 



