VIU PREFACE. 



ganization, constitutes what is usually termed Physi- 

 ology, a science of vast and almost boundless extent, 

 since it comprehends within its range all the animal 

 and vegetable beings on the globe. This ample field 

 of inquiry has, of hite years, been cultivated with ex- 

 traordinary diligence and success by the naturalists 

 of every country ; and from their collective labours 

 there has now been amassed an immense store of facts, 

 and a rich harvest of valuable discoveries. But in 

 the execution of my task this exuberance of materials 

 was rather a source of difficulty ; for it created the 

 necessity of more careful selection and of a more ex- 

 tended plan. 



In conformity witli the original purpose of the 

 work, which I have ail along endeavoured to keep 

 steadfastly in view\ I have excluded from it all those 

 particulars of the natural history both of animals 

 and of plants, and all description of those struc- 

 tures, of which the relation to final causes cannot 

 be distinctly traced; and have admitted only such 

 facts as afford manifest evidences of design. These 

 facts I have studied to arrange in that methodized or- 

 der, and to unite in those comprehensive generaliza- 

 tions, which not only conduce to their more ready 

 acquisition and retention in the memory, but tend 

 also to enlarge our views of their mutual connexions, 

 and of their subordination to the general plan of cre- 

 ation. My endeavours have been directed to give 



