PHYSIOLOGICAL ACTIVITIES OF THE PROTOZOA 101 



The protozoa are, then, complete living organisms, in which no 

 function found in the higher animals is lacking, and we have seen 

 enough of their structures and functions to show how the scope of 

 protozoology leads us into all fields of biological pursuits, from tax- 

 onomy, the description and classification of living things, through 

 morphology, physiology, cytology, psychology, and theoretical biology. 

 In the following chapters I wish to show how this scope widens out 

 and leads us into some of the most difficult, but at the same time 

 fascinating, problems of biology. 



