260 ESSAY ON CLASSIFICATION. 



relations of individuals to the world around them, and to 

 their kindred, and upon the proportions and relations of 

 their parts to one another, as well as upon their ornamenta- 

 tion. Well digested descriptions of species ought, therefore, 

 to be comparative ; they ought to assume the character of 

 biographies, and attempt to trace the origin, and follow 

 the development, of a species during its whole existence. 

 Moreover, all the changes which species may undergo in 

 the course of time, especially under the fostering care of 

 man, in the state of domesticity and cultivation, belong 

 to the history of the species ; even the anomalies and dis- 

 eases to which they are subject, belong to their cycle, as 

 well as their natural variations. Among some species 

 variation of colour is frequent, others never change, and 

 some change periodically, others accidentally ; some throw 

 off certain ornamental appendages at regular times, the 

 Deers their horns, some Birds the ornamental plumage which 

 they wear in the breeding season, etc. All this should be 

 ascertained for each, and no species can be considered as 

 well denned and satisfactorily characterized, the whole 

 history of which is not completed to the extent alluded 

 to above. The practice, prevailing since Linneeus, of 

 limiting the characteristics of species to mere diagnoses, 

 has led to the present confusion of our nomenclature, and 

 made it often impossible to ascertain what were the species 

 which the authors of such condensed descriptions had 

 before them. But for the tradition which has transmitted, 

 generation after generation, the knowledge of these species 

 among the cultivators of science in Europe, this confusion 

 would be. still greater; but for the preservation of most 

 original collections, it would be inextricable. In countries 

 which, like America, do not enjoy these advantages, it is 

 often hopeless to attempt critical investigations upon 



