INTKODUCTION 



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 specula- 

 tions 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 questions, 

 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 became 



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