PROTOPLASM. 



ing the layer of protoplasm which lines the inside of the cell 



wall to collapse, and separate from the wall, drawing the 



chlorophyll band 



inward toward the 



center also. The 



wall layer of proto- 



plasm can now be 



more distinctly 



seen and its gran- 



ular character ob- 



served. 



We have thus 

 employed three 

 tests to demon- 

 strate that this sub- 

 stance with which 

 we are dealing 

 shows the reac- 



tions which we 

 know by experi- 



' Cell of spirogyra before Cells of spirogyra after treatment 



tO be given treatment with glycerine. with glycerine. 



Fig. 4- 



by protoplasm. We therefore conclude that this colorless and 

 partly granular, slimy substance in the spirogyra cell is proto- 

 plasm, and that when we have performed these experiments, 

 and noted carefully the results, we have seen protoplasm. 



11. Earlier use of the term protoplasm. Early students of the living 

 matter in the cell considered it to be alike in substance, but differing in 

 density; so the term protoplasm was applied to all of this living matter. The 

 nucleus was looked upon as simply a denser portion of the protoplasm, and 

 the nucleolus as a still denser portion. Now it is believed that the nucleus is 

 a distinct substance, and a permanent organ of the cell. The remaining por- 

 tion of the protoplasm is now usually spoken of as the cytoplasm. 



In spirogyra then the cytoplasm in each cell consists of a layer which lines 

 the inside of the cell wall, a nuclear layer, which surrounds the nucleus, and 

 radiating strands which connect the nucleus and wall layers, thus suspending 

 the nucleus near the center of the cell. But it seems best in this elementary 

 study to use the term protoplasm in its general sense. 



