xvi CONTENTS 



PAGE 



5. A COMPARATIVE STUDY OF RESPIRATION : Respiration in 

 Single-celled Animals Respiration in the Earthworm 

 Respiration in Fishes Respiration in Air-breathing Ani- 

 mals Comparison of the Organs of Respiration Studied . 229 



CHAPTER XII 

 A STUDY OF THE SKIN AND THE KIDNEYS 



Characteristics of the Skin Uses of the Skin .... 232 



1. ANATOMY AND PHYSIOLOGY OF THE SKIN : Layers of the 



Skin Characteristics of the Epidermis Structure of the 

 Epidermis Structure of the Dennis Nails Hair 

 Glands of the Skin Sebaceous Glands Perspiratory 

 Glands Heat Regulation in the Body .... 233 



2. HYGIENE OF THE SKIN: Importance of Bathing Kinds of 



Baths Care of the Hair Care of the Nails Treatment 

 of Burns Clothing Effect of Alcohol on the Body Tem- 

 perature .... 240 



3. A COMPARATIVE STUDY OF THE SKIN : The Skin of Inverte- 



brates The Skin of Amphibia The Skin of Fishes and 

 Reptiles The Skin of Birds The Skin of Mammals . 244 



4. A STUDY OF THE SHEEP KIDNEY: General Appearance of 



the Kidney Longitudinal Section of the Kidney . . 248 



5. ANATOMY AND PHYSIOLOGY OF THE HUMAN KIDNEY : Posi- 



tion and Appearance Microscopical Structure Course 

 taken by the Urine Importance of the Kidneys Blood 

 Supply of the Kidneys . . ... . . .248 



6. A COMPARISON OF EXCRETORY ORGANS: Secretion and Ex- 



cretion The Kidneys and the Skin The Lungs as 

 Excretory Organs The Liver as an Excretory Organ 

 The Kidneys of Vertebrates The Kidneys of Invertebrates 251 



CHAPTER XIII 

 A STUDY OF THE NERVOUS SYSTEM 



The Body as a Collection of Organs Cooperation of the Organs 



Functions of the Nervous System Parts of the Nervous 

 System 253 



1. ANATOMY OF THE SPINAL CORD: Shape and Size Fissures 



Coverings of the Cord Cross Section of the Cord 

 Nerve Cells and Fibers 256 



