ELEMENTS 



OF 



MAMMALIAN ANATOMY 



INTRODUCTION. 



Since this book is designed for the use not only of 

 students who have pursued the study of biology for some 

 time, but also for those making their first aetual acquaint- 

 ance with the subject, it may be well to call attention 

 to the fact that any animal or plant may be considered 

 from several different standpoints. A general study of 

 structure and of the relations of the various systems and 

 organs is known as Anatomy. Histology concerns itself 

 with the cell and cell aggregates or tissues composing 

 the organs. These two sciences are included in Mor- 

 phology, a term which by many is made to include also 

 Embryology or Ontogeny, treating of the development of 

 an organism from the egg, or its vegetable homologue, 

 to the period of assuming adult characteristics. Since 

 ontogeny deals not only with the growth of structure 

 but also the process of growth, it may likewise be in- 

 cluded under Physiology, a science which has for its 

 province the investigation of the functions of the organs 

 and systems. A special field of physiology having for 

 its consideration the operations, especially the conscious 

 2 17 



