Plants and Their Food 



can not be seen by the naked eye. When greatly magni- 

 fied by the microscope, their simple structure is plainly 

 seen. Each plant is only a single cell, such as shown 



in Fig. 2 a and b. Each one of 

 these plants, or cells, has the 

 power to form daughter plants, 

 that soon become independent. 

 9. Fungi. Yeast belongs to 

 a class of plants called fungi 

 (fun-gi singular, fungus). These 

 fungus plants are very small, 

 but they are very important. 

 The bacteria causing the nodules 

 on peas and clover plants are 

 very beneficial. Some cause dis- 

 ease that destroys other plants, 

 like the rust on oats, mildew on 

 roses and grapes, or the rots of 

 fruits and roots. Other kinds of 

 these simple plants cause disease in animals, as chol- 

 era in swine and chickens. Their food consists of the 

 substances of other plants, or of animals, like starch, 

 sugars, fat, lean 

 meat, white of 

 egg, etc. In order 

 to become famil- 

 iar with the con- 

 ditions which 

 favor the growth 

 of yeast-like 

 plants, we will set 

 up the following 



Fig. 3. Figures of various kinds of Bacteria. (After 

 Cohn and Sachs. Very highly magnified.) 



Fig. 2. Yeast Colonies. A, sur- 

 face view of full - grown 

 plants with young branches 

 or buds. B, view of similar 

 colonies seen as though cut 

 across. Magnified about 750 

 times. 



