VI PREFACE. 



ever, to secure a completeness, and to make the 

 work useful to physicians and others engaged in 

 research, by careful references, and the addition of 

 a bibliography, which he has sought to make accu- 

 rate and extended. Some authors may have been 

 overlooked ; such the writer cordially invites to send 

 him references to their own papers, or to those of 

 others they believe to have a bearing upon the 

 subject. 



332, South Fifteenth Street. 

 February, 1870. 



