CONTENTS 



CHAPTER I 



Parasitism and Disease 



Definition of a parasite, i; examples among various ani- 

 mals, 2; Parasitism, 3; effect on the parasite, 4; how a harmless 

 kind may become harmful, 5; immunity, 6; Diseases caused by 

 parasites, 7; ancient and modern views, 7; Infectious and con- 

 tagious diseases, 8; examples, 9; importance of distinguishing, 

 9; Effect of the parasite on the host, 9; microbes everywhere, 10; 

 importance of size, 11; numbers, 11; location, 11; mechanical 

 injury, 12; morphological injury, 13; physiological effect, 13; 

 the point of view, 14. 



CHAPTER II 



Bacteria and Protozoa 



Bacteria, 15; border line between plants and animals, 15; 

 most bacteria not harmful, 15; a few cause disease, 15; how 

 they multiply, 15; parasitic and nonparasitic kinds, 17; how a 

 kind normally harmless may become harmful, 18; effect of the 

 bacteria on the host, 18; methods of dissemination, 18. Pro- 

 tozoa, 19; Amoeba, 19; its lack of special organs, 19; where 

 it lives, 19; growth and reproduction, 19; Classes of Protozoa, 

 20; the amoeba-like forms, 20; the flagellate forms, 20; im- 

 portance of these, 21; the ciliated forms, 22; the Sporozoa or 

 spore-forming kinds, 22; these most important, 23; abun- 

 dance, 23; adaptability, 23; common characters, 24; ability to 

 resist unfavorable conditions, 24. 



