Of THE 



DIVERSITY 

 or 



INTRODUCTION 



PHYSIOLOGY is really an older science than anatomy, for 

 even before any idea of pulling to pieces, of dissecting the 

 animal machine had suggested itself to our forefathers, 

 crude speculations in regard to the causes and nature of the 

 various vital phenomena must have been indulged in 

 speculations based upon the vivid belief in the action of 

 spiritual agencies, and perhaps unworthy of the name of 

 science. Still the physiology of to-day is the offspring of 

 such speculations. 



Organs and Function. The first great and true advance 

 was through anatomy. As that science showed how the 

 body is composed of distinct and different parts, it became 

 evident that these parts or organs had separate actions or 

 functions ; and hence arose the important conception of the 

 co-relation of organ and function. 



From the early metaphysical speculations to such true 

 inductions was a great stride, for a scientific method of 

 advance had been established. 



Ever since this, until quite recent times, physiology has 

 followed in the footsteps of anatomy, or, to use a more com- 

 prehensive term, of morphology. The connection between 

 organ and function having been demonstrated, the ques- 

 tions, why are these various functions connected with the 

 respective organs ? why should the liver secrete bile, and the 

 biceps muscle contract ? next forced themselves upon the 

 attention. 



Tissues and Function. Again anatomy paved the way 

 for the explanation. The dissecting knife and the early and 

 defective microscope showed that the organs are composed 

 of certain definite structures or tissues, differing widely from 

 one another in their physical characters and appearance, and, 

 as physiologists soon showed, in their functions. It now 



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