4 PROTOZOAN PARASITISM 



freezing and the cysts of some may survive even that 

 temperature. 



Within the bodies of these minute beings occur 

 all of the complex processes of life. They live and 

 move and have a being. They move about purpose- 

 fully, they ingest food, they inhale, they digest, they 

 metabolize, they reproduce their kind. Under un- 

 favorable conditions they sicken and die, under fa- 

 vorable environment their lives and their bodies 

 are continued in their offspring ; they are essentially 

 immortal beings. 



The construction and organization of their bodies 

 is of the simplest, and at the same time complex. 

 The secrets of life are concentrated here in a form 

 which may be seen in toto, the different scenes en- 

 acted in periods of time so short as to be subject to 

 continuous observation. Consequently many have 

 thought and tried to determine what has remained 

 hidden from the mind of man by study of the lives 

 of protozoa. 



ANATOMY AND PHYSIOLOGY 



A protozoon is a minute animal, the organs and 

 systems of which, with their specialized materials, 

 are not separated into anatomical units called cells. 

 The whole body bears physical resemblance to a 

 single cell of the higher animals, in that in a general 

 pattern it is composed of cytoplasm and nucleus, and 

 in that sense is unicellular. Physiologically the pro- 



