AMCEBA 



25 



example, are very complex, their functions or activities 

 are more efficiently performed and they are designated 

 high organisms. This fact involves the principle of the 

 division of labor that will be better understood after we 

 have examined a few examples illustrating simple, more 

 complex and highly complicated types. 



Amceba. — Among the best known examples of a primi- 

 tive organism is the amceba (Fig. 4), living in the mud 

 and slime at the bottom of ponds and gently running 

 streams. Large individuals are barely visible to the un- 

 aided eye, but under the microscope the body is seen to 



Fig. 4. — The Amoeba, showing process of multiplication. 



consist of a drop of semi-fluid protoplasm without an en- 

 closing wall but surrounding a globular nucleus. This 

 animal is thus a single cell. In moving about one part 

 of the body is slowly pushed out in the form of a blunt 

 process, w^hile a corresponding part of the cell is with- 

 drawn, the animal thus flowing along like a sheet of 

 quicksilver moving across an unplaned, gently sloping 

 board. Where a particle of food lies in its path the 

 amoeba pushes it into its soft interior where it is digested 

 without the aid of any structures comparable to a mouth 

 or digestive system. Breathing takes place through the 

 general surface of the body. Cold, heat, and various 



