THESES FROM LITERATURE, 



BUTTNER G. J. : „Aphorismen iiber die Wanderungen der Vogel" 

 „Nauinannia" 1858. 

 1. Migration originates from an indefinable instinct. 

 Brehm, A. E. : „Das Leben der Vogel" 1861. 



1 . The Migration-direction is southwesterly and vice-versa. 



2. Streams and valleys are the highways of Migration. 



3. Deep ridges when in the direction of large valleys, are passages. 



4. Cause of migration : love and hunger. 



Heuglin, Th. von:„Zoogeographische Skizze des Nilgebietes"„Peter- 

 mann's geogr. Mitth." 1869. 



1. The migratory Birds of Europe and Northern Asia wander as 

 far as Central-Africa. 



2. The Migration-direction is N. S. 



3. Coasts and streams are readily followed by Migrants. 

 MiDDENDORF, A. von : „Sibirische Reise" Tom. IV. 1873—74. 



1 . There are Migration-routes, which follow the geographical 

 latitudes. 



2. There are Migration-routes, which follow the geograi^hical 

 longitudes. 



Palmen, I. A: „Uber die Zugstrassen der Vogel" Leipzig 1876. 

 („Om foglarner flyttningswagar" 1874.). 



1 . Migration is a Phenomenon of movement. 



2. Two moments have to be taken into consideration, the time- 

 moment — migration-season - and the space-moment — 

 migration-route. 



3. Birds migrate from their northern breeding stations to the 

 southern ones along certain geographically fixed routes. 



4. As a rule Birds do not migrate beside or between the routes. 



5. Migration-routes, as a rule, run separately or at most meet only 

 at the final point. 



6. The individuals return in spring along the same Migration-route 

 as they travelled in autumn. 



(SB 38 129 



