CHAPTER L 
PARASITIC FUNGI AND MOULDS. 
I. GENERAL REMARKS ON FUNGI. 
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 trufile 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 soil, but also, and 
chiefly, by decomposing the carbonic acid of the air, 
assimilating the carbon which, as cellulose, enters 
into the composition of all their tissues, and giving 
forth pure oxygen to the air. 
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