14 PRINCIPLES OF PHYSIOLOGY 



on the study of physiology. One should know 

 something of the plan of structure met with 

 in the great subdivisions of the animal kingdom. 

 The student of human physiology, for exam- 

 ple, should be acquainted with the general 

 anatomy of the human body, and of its various 

 organs, although much may be learned from 

 the dissection of one of the lower mammals, 

 such as the rabbit. Not only is it necessary 

 to study the forms and relations to other 

 parts of the various organs, as seen by the 

 naked eye, but also the minute structure of the 

 organs and tissues as revealed by the micro- 

 scope, and by modern technical methods of 

 preparing these for examination. This is the 

 department known as Histology, a depart- 

 ment of science that in recent years has made 

 enormous progress. The demands of one 

 science stimulate another, and we find an 

 example in the development of the modern 

 microscope, which, both in its mechanical and 

 optical arrangements, may be regarded as a 

 nearly perfect scientific instrument. The 

 methods of hardening, cutting into thin 

 sections, and staining by various colouring 



