RECENSIO CONTRADICTORIA. 



The breeding regions; for our Birds therefore Europe. Deichler. 1. 



— In the glacial period the Tropics; and : The home of our migrating 

 Birds are not the countries where they sojourn in summer, but sou- 

 thern regions. Braun. (II) 2, III (1). 



Passage v. Migration. 



Retiini. Always to the same place. Homeyer. 16. 



Sense for locality i\nd direction strongly developed. Homeyer. 17. 

 (Cf. Instinct p. 89.) 



Settling in the breeding region. Takes place from South to North. 

 Weissmann n. — In certain tropical species the other way, from 

 North to South. Finsch. 1. 



Straggling (imperfect Migration). From mountains to valleys and 

 vice versa. Emperor Frederic. 5. — Severtzoff. 5. In the 

 Tropics from the mountains to the plains. Tristram. 5. 



Weather. Is of influence. Emperor Frederic. 10 — Gatke. 5. 

 Is of great influence. Kjaerbollino. 2. Is of essential influence. 

 Homeyer. 12. — Kessler. 4, 5. — Has no decided influence. Mar- 



TORELLI. 3. 



U^//7«'. Contrary winds hinder Migration. Emperor Frederic. 11. 



— Birdsmigrate with the wind. Homeyer. 2. — Straggle with different 

 winds. Faber. 4. — Travel against the wind. Brehm, Ch. L. 6. 



Winter. The previous wmter has great influence. Brehm, Ch. L. 

 2. — MiDDENDORFF. 8. — A mild winter forces on the spring Mig- 

 ration. Faber. 2. 



The above summary is noteworthy in many respects. It proves that 

 besides many congruent observations and opinions, there are others 

 in direct contrast and no few merely hypothetical. Really, it is a field in 

 which every thinking Ornithologist may create new Theses to any extent 

 and more or less incredible. But whether in support of real and posi- 

 tive knowledge, may strongly be doubted. I only remember the stri- 



B3) 62 IB 



