PRELIMINARY REMARKS. 3 



others ; and the object of the observers has been by no means to elucidate the multiplicity of the 

 plumage in individual cases, but rather to explain the structure of feathers in general. 



I may, therefore, flatter myself with the hope of awakening the interest of naturalists by the 

 announcement of my new results, and, by the enumeration and detailed description of the 

 feathered regions of the bodies of birds, to which I give the name of feather-tracts (pteryla, 

 Federnfluren), of proving that these, new 1 and surprising as they may appear to many on the first 

 glance at my figures, really furnish equally significant and important characters for the certain 

 and natural discrimination of the families of birds. Since I have recognised this truth I have never 

 ceased employing all the means at my command for its further demonstration, being convinced 

 that the correct and natural limitation of the subordinate groups is one of the chief problems of the 

 naturalist, the solution of which is not to be attained by a schematic treatment, often simply in 

 accordance with this or that property, but only by the most laborious investigation of the 

 species from every point of view. 



1 I have myself hitherto only mentioned these feather-tracts in passing (for example, in 

 NAUMANN'S 'Vogeln Deutschlands/ 2nd ed., I, p. 32; and in ERSCH UND GRUBEK'S 'Allgem. 

 Enzyklop./ xxi, p. 147, Art. Certhia, and xxiv, p. 207, Art. Dermorhynchi). But M. JACQUEMIN has 

 recently made some communications of a similar nature to the Academy of Sciences in Paris, of which 

 I know nothing further (see FRORIEP'S 'Notizen Sec./ 1837, p. 170). An academical thesis published 

 by me under the title ' Pterylographiae Avium pars prior :' Halae, 1833-4, was only communicated to a 

 few friends ; it forms the foundation of the first section of the present work. 



