PREFACE. ix 



feeble amplifications of its teachings. Professor Barker 

 was my first teacher in medicine, and to him I am 

 indebted for much more than his graciousness in review- 

 ing these pages and writing the introductory note. 



The only originality claimed is in the presentation 

 of the subject matter. Save in a few instances, specu- 

 lation has not been indulged in, and only accepted 

 doctrines have been adhered to. 



Great pleasure was taken in the writing of these pages, 

 although most of the work was done during moments 

 snatched here and there between urgent duties ; whether 

 I was justified in my undertaking can only be told if 

 others derive either pleasure or profit in their perusal. 



Millard Langfeld. 



203 McCague Bldg., Omaha, Neb. 

 March 25, 1907. 



