18 PRINCIPLES OF PHYSIOLOGY 



of living matter. It would also seem that 

 electricity plays an important part in vital 

 activities, or, at all events, it is intimately 

 related to the intricate and hidden molecular 

 phenomena on which life depends. Finally, 

 the phenomena of the living being can only 

 be accounted for by their consideration in the 

 light of the modern doctrine of the conserva- 

 tion of energy, a doctrine which may be said 

 to have originated in the study of these 

 phenomena. The history of this great idea 

 shows that the endeavour to account for 

 animal heat and the relation of food and 

 oxygen to the production of heat and of 

 animal movements, was one of the first steps 

 towards the building up this doctrine, which 

 lies at the foundation of all physical, chemical 

 and biological science. 



7. Thus, physiology rests on a tripod of 

 three sciences Anatomy, Chemistry, and 

 Physics. It brings to bear on its problems 

 all the information that can be gathered from 

 those sciences, considered in their broadest 

 relations, and while physiology has its own 

 methods, it may be said to be the mechanical 



