298 Dr. J. H. Blasius on the Diversity in the Estimate 



branches of zoology. The sph'it of Linne, Pallas^ and Cuvier 

 ruled the entire domain of zoology. As soon as ornithology 

 hastened forward with moi'e rapid strides, it began to emancipate 

 itself from other branches of zoology, and struck, as regards 

 the conception of species, into a totally different course. The 

 majority of ornithologists of note troubled themselves but little, 

 or not at all, with other departments of zoology ; they found no 

 check upon their efforts in the stricter conception of the other 

 classes of animals ; their conception of species became constantly 

 more and more isolated and, in course of time, looser and less care- 

 ful in comparison with the prevailing zoological procedure. 



For a long time Brehm was the only ornithologist who fol- 

 lowed this bolder conception as a matter of principle. Towards 

 the close of the year 1840, Bonaparte also gradually acquired 

 the same taste ; but he never went so far as that he could have 

 formed a bridge between Brehm and the other ornithologists. 

 In his fundamental views he entirely belonged to the opposite 

 school in ornithology, and vacillated only as to the signification of 

 some local races differing in colour, but similar in form. Gloger, 

 Schlegel, and Thieuemann still endeavoured to maintain the old 

 classical zoological point of view. 



If we examine the ornithological species-question from this 

 zoological point of view, the gap between the two extreme 

 schools becomes still more distinctly marked. Of the above- 

 mentioned 60 doubtful forms, which are regarded by most zoo- 

 logists as varieties, by many ornithologists at different times as 

 species, about 50 would decidedly have to be united with the 

 allied forms. Scarcely ten of these forms would remain as still 

 fluctuating zoologically. According to the views which have 

 hitherto been followed practically by Schlegel, Gloger, and 

 Thienemann, to which I may add my own, the European Ornis 

 would consist of about 425 certain species, 10 doubtful forms, 

 and 100 exotic immigrants. 



On the other hand, Brehm, in his " Vogelfang," cites, besides 

 these 420 certain species, 520 others, of which the boldest orni- 

 thologists of the opposite party mention 60 at the outside, and 

 besides these again, nearly 1400 subspecies. The number of 

 species not certainly well founded with Brehm is fifty times, 



