8 THE MAIN CURRENTS OF ZOOLOGY 



students preparing for the profession of medicine 

 should engage in the study of zoology, not merely as 

 supplying training in the kind of observation that is 

 needed for diagnosis, but as affording a broader 

 outlook on the structure, the development and the 

 physiology of the human body. It affords to-day the 

 best introduction to general physiology. 



In addition to its inseparable connections with 

 botany, zoology is closely related to two other 

 sciences physics and chemistry. Zoology and 

 botany are essentially the sciences of organic nature, 

 while physics is the science of inorganic nature. In 

 the study of nature the biological and physical 

 sciences are fundamental and reciprocal to one an- 

 other. 



Chemistry is somewhat more closely allied to 

 biological phenomena since these phenomena are 

 physico-chemical in their nature and the great 

 development of physiological chemistry has brought 

 it into very close relation with biology. A certain 

 knowledge of chemistry is necessary to the under- 

 standing of any physiological problem. Chemistry, 

 physics and biology form the tripod of sciences 

 essential to the student of medicine. 



Zoology has been made by the confluence of many 



