EDITOR'S PREFACE. 



THE character of the present Work is too well known and established 

 to need any commendation. Within a period of four years, it has passed 

 through three editions both in this country and Great Britain. It will 

 be seen, upon referring to the Author's Preface, that the present edition 

 has been essentially modified and improved ; and, besides attentive re- 

 vision, has undergone material alteration in the arrangement. 



Many of the Notes of the American Editor to former editions have 

 been incorporated by the Author in the text of the present ; others remain ; 

 whilst such additions have been made, as the progress of the science 

 required. 



By the liberality of the Publishers, the Editor has been enabled to add 

 numerous additional illustrations; which, accompanied by copious refer- 

 ences, will, he trusts, be found to enhance the value of this edition, and 

 to peculiarly adapt it to the Student of Physiology. There are one 

 hundred and fifteen more wood-cuts in this than in the third English 

 edition, and one hundred and one more than in the last American. 



The new matter added by the American Editor is in smaller type, and 

 is distinguished thus [ M. C.] The new cuts are included between 

 brackets [ ]. M. C. 



230 ; Spruce Street, Philadelphia, 

 September, 1847. 



