PREFACE TO THE SECOND EDITION vii 



often been compelled to represent matters as they are at present understood, 

 although convinced of the insufficiency of the accepted facts and inter- 

 pretations. In any case, I cannot send forth even this revised edition with 

 the feeling that I have attained what I desired. 



Those works which have appeared since the manuscript was finally given 

 to the press have not been noticed in the text. Hence for the first chapter 

 of Vol. I, the references to the literature cease with the beginning of 1896. 

 Notices of the more important works which have appeared subsequently 

 have, however, been inserted while the book has been in the press. 



It is a pleasant duty to record my grateful thanks to Dr. Klemm and 

 Dr. Giessler for their kind assistance in the correction of the proofs. 



W. PFEFFER. 



LEIPZIG, September 24, 1897. 





