• CHAPTER L 



PARASITIC FUNGI AND MOULDS. 



I. General Remarks on Fungl 



Every one is acquainted with the field and forced 

 mushrooms, two varieties of one and the same species, 

 wild or cultivated, and often seen at table. It is less 

 generally known that the truffle is also a fungus: 

 and that the large class of fungi includes moulds and 

 many parasites which are more or less microscopic, 

 which live at the expense of wild and cultivated 

 plants, and attack animals and also the human subject. 

 Fungi are among the lower plants, and differ from 

 higher orders in their mode of life. It is well known 

 that the large majority of plants are not nourished only 

 by absorbing the mineral salts which, in a state of 

 solution, their roots derive from the soU, but also, and 

 chiefly, by decomposing the carbonic acid of the air, 

 assimilatiag the carbon which, as cellulose, enters 

 into the composition of all their tissues, and giving 

 forth pure oxygen to the air. 



