districts so widely separated as Central Germany, Heligoland, 

 the eastern coast of Great Britain — including the Orkney and 

 Shetland Islands— Norway, up to a latitude of 70° N. in Finmark, 

 the same results as to the direction of the migratory flight have 

 been obtained. The latitudinal range of this migration front 

 covers a stretch of no less than 960 geographical miles . . ." 

 When it can be shown, as it undoubtedly can, that the breeding 

 range of certain species — which according to his theories migrate 

 east and west — entirely covers this distance, then, after also 

 taking into consideration the estimated numbers of these 

 species migrating past Heligoland alone, the full significance 

 of his theory of a broad migratory column corresponding to the 

 latitudinal area of the breeding range will be fully appreciated. 



To return -now to his views on the direction of the migra- 

 tory flight. " Direct observations in Heligoland," he remarks, 

 " either from watching the flight of passing migrants by day, or 

 by noting their call-notes during the night hours, have established 

 the following main results with regard to the direction of the 

 migration flight, viz., that in autumn the migration proceeds 

 from east to west and in the spring in the opposite direction. 

 Further, that in the cases of all the species and individuals noted 

 on the island, these courses are rigidly maintained during the 

 passage, and such rare deviations as do occur never extend 

 beyond one or two points of the compass. Not all birds, how- 

 ever, reach their winter destinations by an autumn passage 

 proceeding in this simple westward direction. Many on the 

 other hand are sooner or later obliged to turn southwards in 

 order to reach the lower latitudes in which their winter quarters 

 are situated ; in the case of some species the original direction of 

 flight is maintained throughout the whole immense stretch of 

 road from the eastern countries bordering the Amoor river to 

 the west of Spain." Herr Gatke here seems to have overlooked 

 the fact that there is a difference in the latitude of the Amoor 

 Valley and the west of Spain of ten degrees, or say seven 

 hundred miles, but of course in so long a journey this does 

 not proportionately amount to much. A flight, however, 

 between these two points can hardly be said to be performed 

 in a rigidly maintained east to west direction. 



