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 actual 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 Morphology, 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 assum- 
ing adult characteristics. Since ontogeny deals not only 
with the growth of structure but also the process of growth, 
it may likewise be included 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 operations of the nervous system, constitutes the 
science of Psychology. 
The same species of animals are not found in all parts 
of the world. The lion and tiger are found wild only in 
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