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TRANSLATOR'S PREFACE 



SINCE this work appeared in German in 1907 certain parts of the 

 text have been extended by Professor Axenfeld, and the references to 

 a number of later publications included. Although the whole of the 

 literature for 1907 has not been analyzed and included in the lists, all 

 the recent work of importance, or which modifies in any way views 

 previously held, has been incorporated in the text. The aim of the 

 translator has been to keep as close to the original as possible ; the 

 carrying out of this aim has been facilitated by the kindness of the 

 author in looking over the proofs. 



The nomenclature used throughout is that authorized by the 

 College of Physicians of London, and where that standard failed for 

 example, in the name of an organism the name used by the first 

 writer on the subject has been used in all cases where that could be 

 determined. 



The greatest care has been exercised to have the references exact. 

 Regarding many foreign names of persons, it will be noted that the 

 German spelling of Russian and other words has been followed. This 

 is done because most of their work has been published or reviewed in 

 that language. 



The importance of the subject, and the difficulty encountered by 

 students in being driven to the original literature for every reference, 

 together with the intrinsic merit of the work, are the reasons why it 



has been translated into English. 



ANGUS MACN>B. 



