MANUAL OF PHYSIOLOGY. 



CHAPTER I. 



THE OBJECTS OF PHYSIOLOGY. 



Biology, the science which deals with living beings, 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 Ani- 

 mal 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 includes the external form, the general construc- 

 tion or anatomy of organisms, and the minute structure of their 

 textures as revealed by the microscope. This latter branch of 

 study, under the name Histology, has now developed into a very 

 extensive subject, which is inseparable from either physiology or 

 anatomy. In this country histology is commonly taught in the 

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