INTRODUCTION. 



We have much to say of Life, or vital activity, in the 

 course of our study of Physiology ; but the most that we 

 know of it is seen in its results. What Life is, or where its 

 precise position is, we are not able to determine. We dis- 

 cover one thing, however, that all the parts of the body 

 are united together with wonderful sympathy, so that one 

 part cannot be injured and other parts not suffer damage. 

 It is further evident that all organs are not equally im- 

 portant in carrying on the work of Life; for some may 

 temporarily suspend their action, without serious results 

 to the system, while others must never cease from acting. 

 Yet there is nothing superfluous or without aim in our 

 frames, and no part or organ can suffer harm without 

 actual loss to the general bodily health. On this point 

 Science and Holy Writ strictly agree. 



