CHAPTER IX 



THE RISK OF PHYSIOLOGY 

 Harvey Haller Johannes Muller 



Physiology had a parallel development with anatomy, 

 but for convenience it will be considered separately. Anatomy 

 shows us that animals and plants are wonderfully con- 

 structed, but after we understand their architecture and even 

 their minute structure, the questions remain, What are all 

 the organs and tissues for? and what takes place within the 

 parts that are actually alive ? Physiology attempts to answer 

 questions of this nature. It stands, therefore, in contrast 

 with anatomy, and is supplementary to it. The activities of 

 living organisms are varied, and depend on life for their 

 manifestations. These manifestations may be called vital 

 activities. Physiology embraces a study of them all. 



Physiology of the Ancients. — This subject began to at- 

 tract the attention of ancient medical men who wished to 

 fathom the activities of the body in order to heal its diseases, 

 but it is such a difficult thing to begin to comprehend the 

 activities of life that even the simpler relationships were im- 

 perfectly understood, and they resorted to mythical explana- 

 tions. They spoke of spirits and humors in the body as 

 causes of various changes ; the arteries_ were supposed to 

 carry air, the veins only blood ; and nothing was known of the 

 circulation. There arose among these early medical men 

 the idea that the body was dominated by a subtle spirit. 

 This went under the name jmcutna, and the pneuma-theory 

 held sway until the period of the Revival of Learning. 



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