PREFACE 



THE effort has been made in this book to unify the study of the 

 parts and the functions of the human organism by the application of 

 approved pedagogical and scientific principles. The teaching of any 

 science proceeds logically from that which is known to that which is 

 not known. Physiology is one of the earliest of the natural sciences 

 to be presented for formal study in school. In respect to man's 

 organism the one sort of knowledge absolutely original and elemental 

 is consciousness conscious motion and sensation. This it is that 

 forms the most apparent difference between the two kingdoms which 

 manifest the phenomena of life. It is characteristic of animals to 

 possess consciousness, volition, feeling. Plants are, to all appearance, 

 devoid of them all. 



Hence this study of human physiology is made to begin with that 

 part of the body which is the organ of consciousness the nervous 

 system. The pupil knows that he thinks and feels and wills and 

 moves, and he studies physiology in order to understand the appara- 

 tus by which these wonders are accomplished. He is here given first 

 (after a few preliminary definitions) a brief sketch of the parts com- 

 posing the nervous system. Next he studies those physical operations 

 into which consciousness enters as an essential quality, and becomes 

 familiar with the organs of motion and sensation. This leads natu- 

 rally to consideration of the provision for the sustenance of those 

 organs nutrition in its comprehensive sense. Finally the student 

 comes to a more detailed examination of the mechanism for the 

 conscious activities of the human being. 



Whatever may be true of philosophers, the infant begins the study 

 of physiology at the point here suggested, and follows a method in 

 harmony with this plan. More than one practical teacher has worked 

 out a similar method through years of experience in the class room. 

 By making the nervous system (the center and core of all animal 

 life) the leading thought throughout, a unity of impression is secured, 



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