FUXGI 



101 



long would it take a pair of elephants to iiniltiply to a mass 

 of the same weioht ? 



Size. As Ave have seen, mere size counts for little. Bac- 

 teria, the smallest [)lants known, are inrniiteVy more powerful 

 than sequoias or whales. Fungi range in size from the giant 

 puffball (the fruiting body of which may grow to tln-ee or even 

 four feet in diameter) to microscopic bacteria, and some of 

 these are quite possibly too minute to be visiljle under our 

 best microscopes. In the fruiting portion of a large mushroom 

 we see but a small part of tlie whole fungus. This consists, as 

 we shall see later, of a feltwork of microscopic threads (the 



g '■-■■■ 



A^^ ■ B 



Fig. 92. Size of microscopic fungi 



Comparative size of : J, a, molds ; h and c, yeasts ; r7, haeteria equally magnified ; 

 B, e, miuLite particle of dust; /, point of finest caml)rie needle; g, baeteria iindi'r 



less magnification. After Conn 



feeding, or vegetative, portion), which permeate the soil, leaf 

 mold, wood of a tree, or other substance in which the plant is 

 growing, possibly'for many feet in every direction. 



Yeasts {Saccharomycetesy the sugar fungi — saccharon, "sugar" ; 

 myces, "fungus"). Yeasts are the " sweet tooth" fungi, and 

 their work in nature is to break down sugars by the process 

 known nsfermenfatioif. The end products are alcohol, carbon 

 dioxide, and various oils and flavors characteristic of ditTerent 

 species of yeast. 'J1ie process of fermentation is re[)resented 

 by the following simple chemical equation : 



Cc",A = 2CJIO + 2C(\ 



• Sugar Alcohol Carbon Dioxide 



Size and color. Common yeast plants are spherical or ellip- 

 soidal bodies about 3 ^/Q■^ of an inch in diameter: a cake of 



