HISTORICAL 101 



muss jedoch ein wirkliches Gleichgewicht eintreten. Man 

 halt dieses Gleichgewicht ftlr erreicht wenn sich die tlber- 

 lebenden Pflanzenformen in bestimmten Proportionen ver- 

 jiingen und keineneuen Elemente weiter eindringen kOnnen. 

 Die sogenannte Schlussf ormation ist nunmehr gebildet. ' ' 



Krause (1892, 1893) studied the origin of the heaths and 

 meadows of northern Germany, reaching the conclusion that 

 the former had for the most part arisen from forests by 

 reason of cultural changes, while the latter also had resulted 

 from changes wrought by man in swamp and moor. Fla- 

 hault and Gimbres (1894) found Arthrocnemum macrostachyum 

 to be the pioneer on the low saline alluvium at the mouth of 

 the Rhone. Afterwards, Salicornia, Atriplex and Aeluropius 

 established themselves and were in their turn finally dis- 

 placed by a very different vegetation consisting of Juniperus 

 and Pinus. Wojeifcow ((894) gave a very complete summary 

 of the way in which man affects vegetation, considering 

 especially the results of those activities which destroy plant 

 coverings and consequently initiate succession. 



Warming has not only contributed very largely to the 

 investigation of succession, but he has also made (1895) the 

 first comprehensive summary of the many scattered results 

 obtained in this field. He has considered the changes of 

 vegetation under three heads, which correspond closely to 

 different types of succession : "(1) Neuer Boden (2) Durch 

 langsamer Veranderungen auf bewachsenem Boden hervor- 

 gerufene Vegetationsveranderungen. (3) Vegetationsver- 

 anderungen ohne Veranderungen im Klima oder im Boden." 

 The following statement constitutes the first attempt to 

 deduce from various sources the general rules underlying 

 the principle of succession. ' 'Es ist schwierig, schon jetzt 

 etwas AUgemeines liber die auf einem neuen Boden auf- 

 tretende Vegetation zu sagen, weil es dariiber wenige 

 eingehende Untersuchungen giebt : jedoch scheint folgendes 

 aus diesen hervorzugehen (vgl. Hult, Grevillius, u. a.). 

 1. Die erste Vegetation ist offen. Es vergeht immer einige 

 Zeit, bevor sich eine zusammenhangende Vegetationsdecke 



