CHAPTER I. 



AN EPITOME OF THE HISTORY OF PHYSIOLOGY. 



The word physiology now used to designate this and 

 kindred subjects, has a very remote origin. Etymologi- 

 cally it means a discourse on nature, from the Greek words 

 physis (0"'<H?), meaning nature, whence the word physical, 

 and logos (?-<w), meaning a discourse. In this original 

 sense it was employed by the earliest writers to include all 

 the natural sciences. Soon astronomy was set off as a spe- 

 cial science, and the term restricted to all subjects that 

 deal with natural phenomena and natural objects close at 

 hand. Little by little as human knowledge widened, 

 and the accumulated observations and experiments in 

 any one field became considerable, this field was sepa- 

 rated from the general study of nature, physiology, and 

 designated by its own peculiar name. In this way the 

 accumulating facts in the domain of chemistry gave rise to 

 the alchemy of the Middle Ages, and when later alchemy 

 was stripped of its superstitions and fancies, it rose to the 

 dignity of the science of chemistry. Soon purely physical 

 facts were separated off as the science of natural philosophy 

 and have become the science of physics. This eliminating 

 process has continued with the progress of science until the 

 original term physiology, which means the study of entire 

 nature, has been contracted so as to apply only to that 

 science which seeks to explain vital phenomena, be it in 

 plant or in animal. 



Etymologically physiology is the parent science and all 

 others outgrowths of it. But not only in an etymological 

 sense is physiology of early origin. While logically phys- 

 iology follows physics, chemistry, botany and zoology, and 



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