It was evident to me that if all the areas of Europe were 

 to work out their material according to a uniform method, we 

 could obtain a positive substratum which would throw much light 

 upon the phenomenon of the migration of birds. 



By dividing the material into historical and recent, there was 

 a possibility of ascertaining the value of MIDDENDORFF'S ,,Wust" 

 (chaos) which was and is still of the greatest interest for science. 



So, in 1891, I adopted and applied the following method: 



HISTORICAL DATA 

 Chimney Swallow (Hirundo rustica L.) 



Aprilis 3. Chymes . . . 1876, 



3. Chymes . . . 1888, 



3. Chymes . . 1890, 



4. Medgyes . . . 1860, 

 4. Koszeg . . . 1880, 



4. Chymes . . . 1879, 



4. Chymes . . . 1883, 



4. Medgyes . . . 1860, 



4. Medgyes . . . 1861, 



4. N.-Enyed . . 1883, 



5. Mezo-Zah . . 1868, 

 5. N.-Enyed . . 1887, 



5. Iglo .... 1883, 



6. Fogaras . . . 1887, 

 6. Szt-Margit . . 1889, 

 6. Chymes . . . 1875, 

 6. Chymes . . . 1886, 

 6. Rozsnyo . . . 1866, 

 6. Sopron . . . 1882, 

 6. Budapest . . 1887, 



6. Okka .... 1889, 



7. Chymes . . . 1880, 

 7. Chymes . . . 1887, 

 7. Budapest . . 1880, 

 7. Sopron . . . 1889, 



7. Rozsnyo . . . 1867, 



7. Rozsnyo . . . 1868, 

 8. Koszeg . . . 1877, 



8. Chymes . . . 1873, 

 8. Chymes . . . 1877, 

 8. Chymes . . . 1885, 



