•Preface. ix 



have been due to the circumstance that the form in which the 

 subject was presented in it was the one best adapted to attain 

 the object proposed ; it could scarcely be that there was any- 

 thing new in it. Hence the form and limits of the second 

 edition which is now demanded are alike prescribed to me ; 

 it must be made as like as possible to the first. This has been 

 done ; the original frame is unaltered, and the old matter still 

 appears in it in many places. On the other hand, much pro- 

 gress has been made in the period which has elapsed since the 

 work was originally composed, and some new views have been 

 laid down which could not be disregarded. The new edition, 

 therefore, will be found to contain not only some editorial 

 improvements in the special descriptions, but also various 

 important alterations. 



These observations apply also to the notes at the end of the 

 work, except that I have introduced somewhat more critical and 

 explanatory remarks than in the first edition. 



A. DE BARY. 



Strassburg, Oct., 1886. 



