GENERAL MORPHOLOGY OF PLANTS 



as temperature, healthy state of the plant, etc., this gliding of 

 the particles or apparent streaming of the protoplasm down one 

 side of the "cell," and back upon the other, continues in an 



uninterrupted rotation. There 

 are many nuclei in an internode 

 of nitella, and they move also. 



REVIEW OF THE GREEN 

 ALG^E. 



384. Importance of study- 

 ing the green algae. There 

 are several important reasons 

 for studying even a few members 

 of the green algae. First. They 

 are generally of simple structure, 

 either single-celled or filament- 

 ous, and serve as excellent ob- 

 jects, easily prepared, for micro- 

 scopic study of the cell and its 

 contents, the processes of absorp- 

 tion, plasmolysis, etc. Second. 

 The sexual organs and methods 

 of reproduction are simple and 

 easily studied. Third. It is 

 believed that some members of 



ciiioruuiiyu uuuicb ciiiu. me ncunai iin<j yix ./. , 1 . 



The direction of the currents of protoplasm the green algae, existing perhaps 

 is indicated by the arrows. , ,. 



ages ago, were the ancestors of 



the higher green plants. It is therefore of interest to study a 

 few types to see how the green algae themselves are organized, 

 and show among themselves different stages in this process of 

 evolution from simple organisms consisting of a single cell to 

 the more complex ones where cells are united into threads, cell 

 plates and cell masses. 



385. Increase in the complexity of the plant body.* The 

 simplest condition of the plant body is found in such plants as the 



* For reference, or special assignment. 



Fig. 200. 



Portion of the end of "leaf " of Nitella 

 with two "leaflets," showing arrangement of 

 chlorophyll bodies and the neutral line (N.). 



