CiiAP. II. SPECIES. 169 



meadowf, fields, dry lands, salt deserts, sandy deserts, moist land, forests, shady groves, 

 sunny hills, low regions, plains, prairies, high table-lands, mountain peaks, or the 

 frozen barrens of the Arctics, etc.; 3d, in their dependence upon this or that kind 

 of food for their sustenance ; 4th, in the duration of their life ; 5th, in the mode 

 of their association with one another, whether living in flocks, small companies, or 

 isolated ; Gth, in the period of their reproduction ; 7th, in tlie changes they inidergo 

 during their growth, and the periodicity of these changes in their metamoq)hosis ; 

 8th, in their association with other beings, which is more or less close, as it 

 may only lead to a constant association in some, whilst in others it amounts 

 to parasitism ; 9th, specific characteristics are further exhibited in the size animals 

 attain, in the proportions of their parts to one another, in their ornamentation, 

 etc., and all the variations to which they are liable. 



As soon as all the facts bearing upon these different points have been fully 

 a.scertained, there can remain no doubt respecting the natural limitation of species ; 

 and it is only the insatiable desire of describing new species from insufficient data 

 which has led to the introduction in our systems of so many doubtful species, 

 which add nothing to our real knowledge, and only go to swell the nomenclature 

 of animals and plants already so intricate. 



Assuming then, that species cannot always be identified at first siglit, that it 

 may require a long time and patient investigations to ascertain their natural limits ; 

 assuming further, that the features alluded to above are among the most promi- 

 nent characteristics of species, we may say, that species are based upon well 

 determined relations of individuals to the world around them, to their kindred, and 

 upon the proportions and relations of their parts to one another, as well as upon their 

 ornamentation. Well digested descriptions of species ought, therefore, to be com- 

 parative ; 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 cour.se of time, especially 

 under the fostering care of man, in the state of domesticity and cultivation, belong 

 to the liistor}^ of the species ; even the anomalies and diseases to which they are 

 subject, belong to their cycle, as well as their natural variations. Among some 

 species, variation of color is frequent, others never change, some change periodi- 

 cally, otliei's accidenttdly ; some throw off" certain ornamental appendages at regular 

 times, the Deers their horns, some Birds the ornamental plumage the}' wear in 

 the breeding season, etc. All this should be ascertained for each, and no .species 

 can be considered as well defined and .satisfactorily characterized, the whole history 

 of which is not completed to the extent alluded to above. The practice prevailing 

 since Linnajus of limiting the characteristics of species to mere diagnoses, has led 

 to the present confusion of our nomenclature, and made it often impossible to 



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