XIII. SINGLE-CELLED ANIMALS CONSIDERED AS 



ORGANISMS 



Problems, — To deterinifie: 



(a) How a one-celled animal is influenced by its environ- 

 ment. 



(b) How a single cell performs its functions. 



(c) TJie structure of a single-celled animal. 



Laboratory Suggestions 



Laboratory study. — Study of paramoecium under compound microscope 

 in its relation to food, oxygen, etc. Determination of method of move- 

 ment, turning, avoiding obstructions, sensitiveness to stimuli. Drawings 

 to illustrate above points. 



Laboratory demonstration. — Living paramoeicium to show structure of 

 cell. Demonstration with carmine to show food vacuoles, and action of 

 cilia. Use of charts and stained specimens to show other points of cell 

 structure. Laboratory demonstration of fission. 



The Simplest Plants. — We have seen that perhaps the simplest 

 plant would be exemplified by one of the tiny bacteria we have 

 just read about. A typical one-celled plant, however, would 

 contain green coloring matter or chlorophyll, and would have the 

 power to manufacture its own food under conditions 

 giving it a moderate temperature, a supply of water, 

 oxygen, carbon dioxide, and sunHght. Such a sim- 

 ple plant is the pleurococcus, the tiny green plants 

 Pieurococcus. A seen on the shady sides of trees, stones, or city 

 pb!nt ceiL ^ ^ houses. Thls plant would meet one definition of a 

 cell, as it is a minute mass of protoplasm contain- 

 ing a nucleus. It is surrounded by a wall of a woody material 

 formed by the activity of the living matter within the cell. It also 

 contains a little mass of protoplasm colored green. Of the work 

 of the chlorophyll in the manufacture of organic food we have 



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