CHAPTER I 

 INTRODUCTION 



Physiology and Other Sciences. Physiology has been 

 well defined as "the physics and chemistry of living 

 matter." If this is a fair statement it is a peculiarly ad- 

 vanced and difficult sort of physics and chemistry, for it 

 has to do with reactions and compounds of the most com- 

 plex description. It could not be developed far until 

 the physics and chemistry of non-living matter had pre- 

 pared the way. Another science also had to come before 

 it, namely, anatomy, the study of the structure of organ- 

 isms. This was a field in which progress could be made 

 independently of other discoveries and it is not strange, 

 therefore, that so early as the sixteenth century a large 

 mass of anatomic knowledge was embodied in monu- 

 mental books with finely executed plates that still com- 

 mand admiration. The principal object of study and 

 delineation was the human rather than the animal organi- 

 zation. In the next century anatomy became broadly 

 comparative, extending to many forms, and at the same 

 time it became minute, such poor microscopes as were 

 available being diligently employed. 



But the seventeenth century is most likely to be asso- 

 ciated in our thought with Descartes and Boyle, Galileo 

 and Newton, men who were preeminently physicists or 

 astronomers. The contemporary chemistry was limited 

 and confused. It was natural that the great addition to 

 physiologic knowledge made in this period should have 

 been in the realm of physics. This was the conception 

 of this circulation of the blood. The arguments in sup- 

 port of the doctrine were marshalled by William Harvey 

 in 1628 in such a telling fashion that it was soon univer- 



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