Q-P34 

 T6I 



v, 6" 



18*74- 



PBEFACE. 



THE present volume completes the task, begun eleven 

 years ago, of preparing a work, intended to represent the 

 existing state of physiological science, as applied to the func- 

 tions of the human body. The kindly reception which the 

 first four volumes have received has done much to sustain 

 the author in an undertaking, the magnitude of which he 

 has appreciated more and more as the work has progressed. 



An elaborate treatise on the great subject of the physi- 

 ology of man must be written, in this country, under certain 

 disadvantages ; and the attempt to give a fair and complete 

 account of certain subjects has often seemed well-nigh hope- 

 less. It soon became evident, in the progress of the work, 

 that it is frequently unsafe to take references at second- 

 hand, even from the best writers ; and months of delay in 

 the appearance of each volume have been due to the necessity 

 of looking up citations, as it was desired to make reference 

 only to original works. There are no complete libraries on 

 physiology in this country ; and, while the author has derived 

 great assistance from the serial publications contained in the 

 Astor Library which he takes this occasion to acknowledge 

 most gratefully he has been compelled to import the greater 



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