INTRODUCTION. 23 



that in the study of human anatomy a knowledge of the form, con- 

 struction, and arrangement of the organs in different types of animal 

 life is essential to its correct interpretation ; it follows also that in the 

 investigation and comprehension of the complex problems of human 

 physiology a knowledge of the junctions of the organs as they manifest 

 themselves in the different types of animal life is indispensable. 

 As many of the functions of the human body are not only complex, 

 but the organs exhibiting them are practically inaccessible to in- 

 vestigation, we must supplement our knowledge and judge of their 

 functions by analogy, by attributing to them, within certain limits, 

 the functions revealed by experimentation upon the corresponding 

 organs of lower animals. This experimental knowledge, corrected 

 by a study of the clinical phenomena of disease and the results of 

 post-mortem investigations, forms the basis of modern human physi- 

 ology. 



