xiv INTRODUCTION. 



as a standard ; and acquires importance from the mutual illus- 

 trations it affords in structure and function. 



The study of anatomy, more, perhaps, than that of most other 

 sciences, will be found to be facilitated by systematic arrange- 

 ment ; and the nearer approach this makes to the end we have 

 in view in such study (which is, primarily, physiology), the 

 greater seem to turn out the advantages therefrom resulting. 

 For this reason, in the work before us, a physiological systema- 

 tization has been preferred ; by which, parts and organs co-ope- 

 rating to one common end or purpose, will be found classed to- 

 gether in the same system. Co-operation in function, however, 

 so far from indicating identity of structure, is in many instances 

 effected by organs of structures the most dissimilar ; while, on 

 the other hand, similarity of texture pervades many parts be- 

 longing to different physiological systems : two facts that may 

 be adduced as forming some objection to the classification here 

 adopted. But, we conceive, they are both overruled by the 

 insight which the present plan gives us into physiology ; the ob- 

 ject, let it never be forgotten, we have in view in prosecuting 

 anatomy. The following table exhibits the 



