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MANUAL OF PHYSIOLOGY. 



CHAPTER I. 



THE OBJECTS OF PHYSIOLOGY. 



Biology, the science which deals with living beings and the 

 phenomena exhibited by them, may be divided into two great 

 branches, viz. : 



1. Morphology, which treats of the forms and structure of the 

 bodies of living creatures. 



2. Physiology, which attempts to explain the modes of activity 

 exhibited by them during their lifetime, and may, therefore, be 

 defined as the science which investigates the phenomena presented 

 by the textures and organs of healthy living beings; or, in short, 

 the study of the actions of organisms in contradistinction to that 

 of their shape and structure. 



The organic or living world is naturally divided into the An- 

 imal and Vegetable kingdoms. We have, therefore, both animal 

 and vegetable morphology and physiology. In studying the veg- 

 etable kingdom, the form and the structure, as well as the activity 

 of plants, are associated together in the science known as Botany. 

 The physiology of plants may, therefore, here be omitted ; though, 

 indeed, it cannot be neglected in considering the processes be- 

 longing to animal life. On the other hand, the morphology and 

 the physiology of animals are commonly taught separately, and 

 in the medical curriculum are made distinct subjects. 



Morphology properly includes the external form, the general 

 construction or anatomy of organisms, and the minute structure 

 of their textures as revealed by the microscope. This latter 



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