CHAPTER XVI 



ECONOMIC IMPORTANCE OF THE STUDY OF 

 THE PROTOZOA 



PROTOZOA and man have been said to represent 

 the extremes of organization in the animal 

 world. They certainly afford striking contrasts. 

 The structure of the Protozoon is very simple, that 

 of man most complex. The concentration of 

 functions in the protozoal organism is infinitely 

 superior to that of man, where specialization has 

 reached almost its finest limits. The career of man, 

 the complicated, is often determined by that of the 

 simple Protozoon, and great human enterprises 

 have failed because of the intermediation of these 

 unsuspected foes in the animal world. The economic 

 importance of the Protozoa is shown in relation to 

 the health of man, to his food-supply, to his means 

 of transport, and even to the place in which it is 

 possible for him to make his home. 



The human body is subject to the attacks of many 

 Protozoa. The skin may be invaded by various 

 species of Leishmania, producing disfiguring sores, 

 or by Spirochaetes that lead to extensive ulcerations. 

 The alimentary canal throughout its length may be 



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