Xll TABLE OF CONTENTS 



CHAPTER XXV 



PAGE 



THE PROTOZOA . . . . . . . , . 218 



Paramecium (218). Life activities of one-celled animals 

 and many-celled animals compared (221). Ameba (222). 

 Euglena (224). Other fresh-water protozoa (224). Parasitic 

 protozoa (227). The malarial parasite (227). Pathogenic 

 protozoa (227). Control of pathogenic protozoa (229). Pro- 

 tozoan parasites of domestic animals (230). Protozoa in 

 drinking water (230). Colonial protozoa (231). Character- 

 istics and classification (233). 



CHAPTER XXVI 



AN INTRODUCTION TO THE VERTEBRATES 234 



The body as a machine (236). Organs and systems of 

 organs (237). Structure of organs (239). Protoplasm (239). 

 Tissues (241). Living and lifeless things (242). The 

 origin of life (244). 



CHAPTER XXVII 



THE FROG, A TYPICAL VERTEBRATE 245 



Movements (245). Croaking (246). Physiological proc- 

 esses (246). Digestion (246). Circulation (248). Respi- 

 ration (250). Excretion (252). Secretion (252). Theskeleton 

 and its functions (254). Muscular activity (256). Nervous 

 activity (256). Sense organs (261). Reproduction (262). 



CHAPTER XXVIII 

 THE LAMPREY EELS AND OTHER CYCLOSTOMES . . . 268 



Form of body (268). Mouth and food (268). Respiration 

 (269). Sensations (269). Internal organs (269). Devel- 

 opment (269). Other cyclostomes (270). The brook lam- 

 prey (270). 



CHAPTER XXIX 

 THE STRUCTURE AND ACTIVITIES OF FISHES . . . .271 



Habitat (272). Form of body (272). Locomotion (272). 

 Protection (273). Sensations (274). Respiration (275). 

 Reproduction (275). 



