PREFACE. 



THE present volume owes its origin to a desire on the part of the 

 Publisher, that an elementary treatise on Physiology should be added 

 to the series of admirable Students' Manuals, on the various depart- 

 ments of Medical Science, which he had previously issued. 



In carrying this desire into execution, the Author has endeavoured 

 to avoid inflicting upon the class for whose use the Treatise is especially 

 intended, the injury of placing in their hands such a superficial and 

 imperfect sketch of the science, as, whilst aifording them but a limited 

 amount of knowledge of its facts, should leave them very ill-informed 

 as to its general doctrines. His object has rather been to convey to 

 the Student as clear an idea as possible of those Principles of Physiology 

 which are based on the broadest and most satisfactory foundation, and 

 to point out the mode in which these principles are applied to the 

 explanation of the . phenomena presented by the living actions of the 

 Human body. In this manner has the Author desired to prepare him 

 for that more detailed study of the latter, which becomes necessary when 

 Physiology is pursued (as it ought to be) in connexion with the changes 

 produced in the living body by Morbific and Remedial Agents, and is 

 thus taken as a guide in the study of the causes, prevention, and treat- 

 ment of Disease which should be the primary object of attention with 

 every one who undertakes the Practice of his Profession. 



Although this Manual combines in some degree the scope of the 

 Author's "Principles of Physiology, General and Comparative," and 

 of his "Principles of Human Physiology," yet it cannot be regarded 

 as a mere abridgment of them, having been written for the most part 

 with very little reference to them, and with every desire to make it 

 complete in itself. As the matter of which these volumes are composed 

 is itself condensed to the utmost practicable degree, it is manifestly 

 impossible that the present Manual should contain more than a mere' 

 outline of the subjects of which they treat. To them, therefore, he 



