SOME TYPES OF FLOWERLESS PLANTS. 233 



sitic or saprophytic plants whicli were formerly all grouped 

 as fungi, but which now are often divided among many 

 classes.' Chlorophyll is absent from fungi, and they are 

 destitute of starch, but produce a kind of cellulose which 

 appears to differ chemically from that of other plants. 

 Unable to build up their tissues from carbonic acid gas, 

 water, and other mineral matters, they are to be classed, with 

 animals, as consumers rather than as producers, acting on the 

 whole to diminish rather than to increase the total amount of 

 organic material on the earth. 



289. Occurrence and Mode of Life of Fungi. — Among the 

 most important cryptogamous plants are those which, like the 

 bacillus of consumption, of diphtheria, of typhoid fever, or 

 of cholera, produce disease in man or in the lower animals. 

 The sub-class which includes these plants is known by the 

 name Bacteria. Some of the most notable characteristics of 

 this group are their extreme minuteness and their extraordi- 

 nary power of multiplication. Many bacteria are on the 

 whole highly useful to man, as is the case with those which 

 produce decay in the tissues of dead plants or animals, since 

 these substances would, if it were not for the destructive 

 action of the bacteria of putrefaction and fermentation, 

 remain indefinitely after death to cumber the earth and lock 

 up proteid and other food needed by new organisms. 



The "rust" of wheat and the "smut" of corn are well- 

 known fungi parasitic on other plants, and the number of 

 such species of fungi already known is not less than 42,000. 

 Pig. 201 shows clearly how a parasitic fungus grows from a 

 spore which has found lodgment in the tissues of a leaf and 

 pushes out through the stomata. 



The largest fungi are those of the group to which the 

 edible mushrooms, the toadstools, piiffballs, and so on, belong. 



1 See Strasturger, NoU, Schenck, and Scliiinper's Lehrbuch, p. 259 ; also Warm- 

 ing's Systematic Botany (translated by Potter), p. 1. 



