6 



FTEST LESSONS IN ZOOLOGY. 



plants and absorb their protoplasm; others engulf silicious- 

 shelled plants (diatoms and desmids) and absorb the pro- 

 toplasm filling them. No animal swallows silica, lime, 

 ammonia, or phosphates as food. On the other hand, 



FIG. 6. A Sun-dew plant. (Natural size.) 



plants manufacture or produce protein in the shape of 

 starch, albumen, sugar, etc., which is animal food. Plants 

 during the assimilation of their food, absorb carbonic acid, 

 and in sunlight exhale oxygen; but while they are growing 

 and performing other functions, they, like animals, con- 

 sume oxygen and exhale carbonic acid. 



