PARAMECIUM CAUDATUM 



63 



sr mil quantity of salt be added (potassium phosphate or potas- 

 sium chloride) the dense structure slowly disappears first in the 

 region around the nucleus and in a few days the protoplasm 

 becomes as clear and vigorous as ever. Such experiments show 

 ei ;her that some of the oxidative ferments are exhausted so that 

 the organisms become gradually overpowered by the products 

 of their own metabolism, or that the formative processes are 

 nc t properly functioning. They also show that salts or elec- 

 trolytes were probably no longer present in the cells and that 



EXPLODED TRICHOCYSTS, 



TRICHOCYSTS 



OIV/DfO MACXONUCLEUS, 



DIVIDING PIICRONUCLEUS. 



DIVIDED MACRONUCLEUS 



FIG. 28. Paramecium in division. Photograph of a section. 



oxidative processes had ceased, because the simple addition of 

 salts to the medium resulted in the restoration of vital activities. 

 Finally they indicate that the nucleus of the cell is the seat of 

 manufacture of the oxidative ferments or catalyzers. 



Reproduction. Like Amoeba proteus and the flagellates 

 Paramecium reproduces by simple division, the micronucleus 

 dividing first. The cell divides transversely through the 

 middle of the macronucleus which is passively divided with the 

 rest of the cell (Fig. 28). New mouths and new contractile 



