HANDBOOK OF PHYSIOLOGY. 



CHAPTER I. 



INTRODUCTORY. 



BIOLOGY is the science that treats of living things, and it is 

 divided into two main branches, which are called respectively 

 Morphology and Physiology. Morphology is the part of the 

 science that deals with the form or structure of living things, and 

 with the problems of their origin and distribution. Physiology, 

 on the other hand, treats of their functions, that is, the manner 

 in which their individual parts carry out the processes of life. To 

 take an instance : the eye and the liver are two familiar examples 

 of what are called organs; the anatomist studies the structure of 

 these organs, their shape, their size, the tissues of which they are 

 composed, their position in the body, and the variations in their 

 structure met with in different parts of the animal kingdom. The 

 physiologist studies their uses, and seeks to explain how the eye 

 fulfils the function of vision, and how the liver forms bile, and 

 ministers to the needs of the body in other ways. 



Each of these two great branches of biological science can be 

 further subdivided according as to whether it deals with the 

 animal or the vegetable kingdom ; thus we get vegetable phy- 

 siology and animal physiology. Human Physiology is a large and 

 important branch of animal physiology, and to the student of 

 medicine is obviously the portion of the science that should 

 interest him most. In order to understand morbid or patho- 

 logical processes it is necessary that the normal or physiological 

 functions should be learnt first. Physiology is not a study which 

 can be put aside and forgotten when a certain examination has been 

 passed ; it has a most direct and intimate bearing in its application 

 to the scientific and successful investigation of disease. It will 

 be my endeavour throughout the subsequent pages of this book to 



K.r. B 



