Protozoa. 291 



energy by which a train is moved is furnished by the 

 burning (oxidation) of coal in the engine. 



7. It produces heat ; heat is another form of energy 

 which always results from oxidation. We are always pro- 

 ducing some heat, even when we are as quiet as possible, 

 and we know that when we are more active we breathe 

 faster and produce more heat. So with the amoeba. But 

 the amoeba should be classed with the so-called " cold- 

 blooded " animals. It should be noted that not only do all 

 such animals have a rather low temperature, but it is a 

 variable temperature and usually only slightly above the 

 temperature of the surrounding air or water. The amoeba 

 is constantly producing heat, but gives'it off to the water 

 about as fast as it is made. 



8. It gives off waste matter, i.e. it excretes. All oxidation 

 produces waste matter. Oxidation of wood or coal pro- 

 duces carbon dioxid, water, and ashes. Our breathing 

 produces carbon dioxid, water, and other wastes which 

 we throw off continually. The carbon dioxid, water, and 

 other wastes thrown off by the amoeba are small in amount, 

 and, being invisible, pass out into the water unnoticed. 



9. It feels ; when a foreign body comes into contact 

 with an amoeba it usually moves. A slight electric shock 

 causes it to assume the spherical form, There is good 

 evidence that amoebae have the sense of touch. They also 

 seem responsive to light and heat. 



10. It reproduces its kind ; this we have seen is done in 

 the simplest way imaginable ; that is, merely by separating 

 into two parts, each of which is then a complete individual. 

 Multiplication takes place by division. 



Paramecium, the Slipper Animalcule. The slipper ani- 

 malcule is usually to be found in the water collected for 

 amoebae. In aquariums where clams have been kept, 



