12 PROTOPLASM AND CELLS 



histolysis, of the entire animal; this shows how essential is 

 the removal of the waste products. 



The Amoeba moves, and it moves of its own accord. It 

 will select one out of several particles of food and move 

 toward it. Thus it is largely automatic in its responses. 



But it is also irritable. If you pass an electric current 

 through the fluid containing an Amoeba on a microscopic 

 slide it will contract into a sphere, thus presenting the least 

 possible surface to the irritant; or it will move away from 

 a chemical that annoys it. But it is difficult to deny that 

 this movement may be a response to some chemical action 

 on the part of the food. Amoebae floating in distilled water and 

 white blood corpuscles, which are very like Amoebae, floating 

 in the liquid of the blood, out of contact with all solid bodies, 

 are said not to throw out pseudopodia. If this be so, it is 

 probably due to the fact that there is an absence of salts in 

 the distilled water. Salts certainly have a marked effect in 

 the production of pseudopodia. Many Amoebae when floating 

 freely in a clear medium throw out a number of fine active 

 radiating pseudopodia. The question of "free-will" in an 

 Amoeba may still be a subject for argument. Still, there is 

 evidence that a certain amount of discrimination can be 

 exercised even by the lowest, unicellular animals. 



The Amoeba, like nearly all animals and plants, respires, 

 that is it takes in oxygen and gives out carbon dioxide, and 

 this it does and they do "all the time." Certain sugars in 

 the cell are oxidized or broken up, potential energy becomes 

 kinetic energy and this takes the form of heat and movement. 

 The chemical result of this reaction or breaking up of the 

 complex molecule is carbon dioxide and water, and these 

 leave the body of the breathing organism by gills, or lungs, or 

 sweat glands, or kidneys, or, as in the Amoeba, by the general 

 surface of the body. 



Protoplasm is reproductive, and the Amoeba exhibits the 

 simplest form of reproduction. First of all, the nucleus 

 divides. Then a waist appears in the Amoeba between the 

 two nuclei; this waist becomes smaller and smaller, but 

 as long as it is there the protoplasm flows through it from 

 side to side. But after a time it snaps, and we have now two 



