394 HEPOKT ON THE MIGRATION OF BIRDS. 



form a basis fur couclusious must be tested, in order that we may judge 

 whether the method adopted is adequate or whether it can be com- 

 pleted in any way. 



It seems liigh time to consider tlie matter from this point of view 

 also, if the scientific cliaracter of the investigation, and with it its pur 

 pose also, is not to be laid at stake. 



That this conception is shared by others we know from the fact that 

 the result of nine years of British observations is now subjected to 

 scientific treatment whose results will surely advance our question; 

 further, from the fact that in Xorth America, in a region where the 

 conditions of the ground offer only small difficulties to the judgment of 

 the direction of migration, an investigation of the time of migration 

 and of the relation of the migration to the meteorological conditions 

 has been undertaken, which has disclosed new points of view. The 

 systematic observation of bird migration along certain lines, started in 

 Hungary in the year 1800, and a statement of which is expected on 

 occasion of the Second International Ornithological Congress in Buda- 

 Pesth, also affords proof that we are not now satisfied with mere obser- 

 vations alone, l)ut want these used scientifically, and that hereby new 

 demands will surely be made of the observation in future. 



Because therefore at present the existence of geographically fixed 

 routes for the individual species is becoming more and more acknowl- 

 edged, and these are to be determined from the material at hand, it 

 seems timely to discuss the question according to the method to be 

 employed. 



Two different methods seem to present themselves, both of which 

 have tlieir advantages and disadvantages : (I) The migration routes 

 of all the species of a certain district are examined by the investi- 

 gators of that district and reproduced cartographically : (2) One species 

 for itself is examined monographically in the largest possible geographi- 

 cal area and reproduced cartographically. 



The first method ofl'ers many advantages. The workers concerned 

 are masters of the language of the district, and the entire local litera- 

 ture is accessible to them, even to the most insignificant writings. 

 They can judge of the reliability of the observers at each station, exer- 

 cise a final control, and complete certain points by correspondence. 

 At all events the native inquirers will thus be able to more completely 

 group all the facts from a given country, as well as to watch over them 

 critically. In the second case the monographer can study more closely the 

 species treated by him, then special variations, their nature, as well as 

 also the specific peculiarities of their flight. He will perceive more read- 

 ily the difference in the flight during the successive sections of the 

 route, or on different routes; in short, the route as a whole can be 

 judged in a more exhaustive manner. 



In the first method the following disadvantage becomes apparent : 

 that in every country, unless it is a very large country, we get only 



