2I 4 



GENERAL MORPHOLOGY OF PLANTS 



Protoplasm 

 in old sense 



Cytoplasm 



[ectoplasm 



portion of it. Now the nucleus is known to be a distinct organ 

 of the cell, while the protoplasm proper is called the cytoplasm, i.e., 

 the cell plasm. Strictly speaking the cytoplasm shows two dif- 

 ferent conditions or kinds, a very thin outer layer next the wall, 

 which is homogeneous, the ectoplasm, and the inner portion, of a 

 granular nature, the endoplasm. The structure of the cell of 

 spirogyra might be recapitulated as follows: 



wall 

 Chlorophyll band 



or 



Chloroplast 



Cell \ Sphere of starch grains 

 Pyrenoid 



jendoplasm 

 Wall layer 

 Nuclear layer 

 Strands 



Nucleus and nucleolus 

 Vacuoles containing cell sap 



351. The structure of the spirogyra cell represents funda- 

 mentally the structure of all living cells in the resting condition, 

 i.e., when the cell is not dividing. The chlorophyll is absent in 

 many cells, and so are the pyrenoid and starch grains. But the 

 cytoplasm, the vacuoles, the nucleus and nucleolus are present 

 in all living cells. The cytoplasm, nucleus and nucleolus con- 

 stitute the living substance of the cell. By reference to fig. 171 

 of the amoeba, a single-celled animal, these important parts of the 

 cell are seen to be present. 



352. Plasmolysis of the cell.* The plant spirogyra is an 

 excellent one in which to study certain work of the cell. In the 



* This subject might well be introduced in connection with the study 

 of methods for strengthening the stem and leaves or in the study of ab- 

 sorption by roots. It is introduced here for the reason that spirogyra is 

 much easier to use than the tissues of the higher plants because no sections 

 are necessary. Also it is convenient in connection with the study of spiro- 

 gyra as a plant. The paragraph is chiefly for reference. 



