44 



PRELIMINARY STUDIES. 



FIG. 21. Protococcus. A cell preparing 

 to divide into numerous small motile 

 cells. 



of the Ferns, Mosses, and other higher plants. 



tractions and expansions 

 of the two cilia which 

 each bears at one end. 

 It will be very . diffi- 

 cult for the beginner to 

 see these cilia. Special 

 means for detecting 

 them are given on page 

 86. A study of these 

 moving forms helps to a 

 better understanding of 

 the motile antherozoids 



Plants and Animals. 



Plants are, in general, characterized by the possession 

 of a cellulose cell wall. Through this wall solutions of 

 nutrient materials pass by osmosis. " These nutrient ma- 

 terials are simple in their nature, consisting mainly of 

 mineral salts tnat form naturally in the soil. In addition 

 to these dissolved nutrients, Morophyl-l earing or holo- 

 phytic plants obtain carbon from the carbon dioxide of 

 the air. The radiant energy from the sun effects the 

 changes which convert these inorganic substances into 

 living protoplasm, which is the life and essential part of 

 every living cell. ChloropJiyl-less or saprophytic plants 

 obtain their carbon from dissolved sugar and their nitro- 

 gen from other organic compounds, which have resulted 

 from previous forms of life. The first steps of the build- 

 ing-up processes have already taken place, and the sapro- 

 phytic plants are not dependent on the sunlight. Plants, 

 in general, are not capable of motion in the ordinary 

 sense, but some of the lowest forms and the reproductive 

 bodies of some of the more highly organized plants are, 



