CONTENTS 



Introduction ........ 



What is Disease? . . . . . . . 



What is Normal Living? ...... 



The Meaning of Abnormal Living .... 



Protective Covering a Basic Factor in Dependence 



Proper Understanding of the Shell or External Skeleton 

 Stabilization, Longevity and Dissolution . 

 Divisions of Geological History .... 



Independence of the First Fauna .... 



General Survey of the Cambrian Fauna of North America 

 The Cambrian Fauna Generally .... 



Precambrian Life ....... 



The Beginnings of Symbiosis and Parasitism 



Complex Character of Parasitism 



Beginnings of Symbiosis ..... 



Eelation of Symbiosis to Parasitism . 

 Illustrations of Primitive Parasitism 



The Case of the Annelids ..... 



The Barnacles ....... 



Early Parasitism of the Snails upon the Crinoids . 



Symbiotic Conjunction of Crinoids and Starfishes 



The Work of Pseudoparasitic Boring Organisms . 

 The Distinction between Protozoan and Metazoan Parasitism 



Sporozoan and Bacterial Parasitism in Geological His- 

 tory 



Summary and Conclusions ...... 



9 

 10 

 15 



20 

 23 



26 

 28 

 29 

 32 

 32 

 35 

 37 

 37 

 38 

 39 

 39 

 61 

 64 

 78 

 80 

 104 



107 

 109 



