122 



ducted, are not of sufficient i-eliabilH)§» on which to establish a 

 theory. He also considers that he has sufficiently explained his 

 views on the direction of the migratory flight in a previous 

 chapter, and that any closer examination of Professor Palmen's 

 arguments is therefore unnecessary. 



When refuting the theories of other ornithologists, Herr 

 Gatke is apt to bring forward those enunciated by himself, as 

 though the latter were equivalent to undeniable facts. However 

 satisfactory they may appear to himself, it would have been 

 better to have awaited their general acceptance before adopting 

 so arbitrary a method of argument. The allusion to his own 

 assertion on p. 140 that it is quite within the power of a bird to 

 cross unaided the entire Atlantic from Newfoundland to Iceland 

 in nine hours, and the frequent references to his own estimates 

 of the speed attained by the Carrion Crow and Bluethroat, are 

 cases in point. 



No theory that has yet been brought forward will, perhaps, 

 account for the means by which every individual species, which 

 may perform an exceptional migration, now finds its way. In 

 objecting to the statement that many birds at the present day 

 conduct their flights over the sea, where at one time there 

 existed groups of islands, or perhaps peninsulars, forming so- 

 called land-bridges, Herr Gatke refers to the case of the Virginian 

 Golden Plover, which species, according to his own views, 

 migrates in one unbroken flight from Labrador to Brazil. Along 

 the whole course of this journey there are no traces that any 

 such land-bridges ever existed. Setting aside the fact that neither 

 has the identity of the flocks passing the Bermudas with the 

 Labrador birds been proved, nor has the exact point at Vi^hich 

 the latter leave the mainland been ascertained ; it does not 

 seem to have occurred to him that this long flight is the out- 

 come of a series of migrations gradually increasing in distance. 

 Apparently, he seems to think that conditions suddenly arose in 

 Labrador necessitating a flight from thence to Brazil, without 

 any intervening development. 



It seems far more reasonable to suppose, however, that this 

 flight has gradually grown from short intermittent journeys along 

 the Atlantic coast, which gradually increased in extent as the 



