THESES. O. HERMAN. 



6. The higher the altitude of the locality, the later the arrival. 



7. The more southerly the locality, the earlier the arrival. 



8. The more northerly the locality, the later the arrival. 



9. The lower the altitude of the locality, the later the departure. 



10. The higher the altitude of the locality, the earlier the departure. 



1 1. The more southerly the locality, the later the departure. 



12. The more northerly the locality, the earlier the departure. 



1 3. Latitudes and longitudes, as regards the Phenomena of Migra- 

 tion, are generally congruent, in the sense that the higher the northern 

 latitude and the higher the locality, the later the arrival and vice-versa. 



14. The progress of Migration is generally isothermal, and is in 

 consequence independent of the pov^er of flight of the migrating 

 species. 



15. The question „Migration-route or movement in a broad front", 

 is incorrectly formulated. Passing Birds follow constant directions, 

 therefore certain routes; in settling the breeding area or breeding zone 

 the result is expansion in the form of repletion. 



16. The settling or colonization in the breeding quarters — much 

 influenced by sexual excitation — a priori excludes a movement in the 

 sense of isepipteses, as well as isotherms and isohypsals. 



17. The settling of the breeding region goes on by tribes.* Between 

 tribes of the same species there is often a large interval according to 

 local features of the region. 



1 8. One and the same species settles often in comparatively southerly 

 or high northerly countries, resulting in a successive arrival, passage 

 and departure. 



19. On the way from the breeding places to winterquarters, or vice- 

 versa, tribes from various settlements of the same species meet and 

 travel in company, and on reaching their places of breeding or hiber- 



* Tribe = (Stamm), means the totality of individuals of a species which settle in a 

 certain district. 



as 20 issi 



