iv PREFACE TO THE GERMAN EDITION 



reference numbers to the authorities cited at the end of the lecture dealing 

 with the subject, and must not be taken as in any sense indicating the 

 date of the discovery of a fact or of the establishment of a theory. I have 

 placed the more recent literature prominently in the foreground, simply 

 because, with its aid, the student can have no difficulty in tracing the older 

 works on the subject ; I do not desire, by this method of citation, to 

 imply that modern works only are worthy of consideration. It has not been 

 possible to enter into the history of the science, save only in a few places 

 where it seemed essential to the elucidation of the subject. 



Only a few of the illustrations are original ; the great majority are 

 reproductions from memoirs or textbooks, and for their execution I am 

 greatly indebted to Fraulein A. Winnecke. A number of cliches have 

 been borrowed from the works of Detmer, Fischer, Goebel, Klebs, Kiister, 

 Strasburger, and Verworn, as well as from the ' Bonn Textbook ' (Lehrb. d. 

 Botanik. Strasburger, Noll, Schenck, u. Schimper). To the authors of 

 these works my best thanks are due for permission to use these illus- 

 trations. 



LUDWIG JOST. 



STRASSBURG, i. E., November, 1903. 



