90 Taxoxomv. 



When we express these invariable properties in words, \^e 

 give the S))ecih'c Character {character specificiis). 



143. 



This idea proceeds on the supposition, that the species which 

 we know, liave existed as long as the earth has had its present 

 form. No doubt there were, in the preceding state of our globe, 

 other species of plants, which have now perished, and the re- 

 mains of which we still find in impressions in shale^ slate-clay, 

 and other floetz rocks. Whether the present species, which often 

 resemble these, have arisen from them ; — whether the great 

 revolutions on the surface of the earth, which we read in the 

 Book of Nature, contributed to these transitions, — we know 

 riot. What we know is, that from as early a time as the 

 human race has left memorials of its existence upon the earth, 

 the separate species of plants have maintained the same pro- 

 ])erties invariably. 



To be sure, we frequently speak of the transitions and 

 crossings of species ; and it cannot be denied that some- 

 thing of this kind does occur, though without affecting the 

 idea of species which we have proposed. We must, there- 

 fore, understand this difference. 



144. 



We perceive the Transitions of a Species, when it loses or 

 changes die properties, which we had considered as invariable 

 in the character. Thus, it would be a transition, if we had 

 stated as an invariable character of winter wheat (Triticum liy- 

 hcrnum)^ that it was biennial, and had an ear without awns ; 

 and if we should remark, that by frequent reproduction, and 

 by very different treatment, it began to assume awns, and, when 

 sown in spring, came to maturity during the same summer. 



But this shews only that our idea of the difference between 

 the two kinds of grains had been incorrect ; for it is the uni- 

 versal rule, that the character does not constitute the species, 

 but the species the character. Species, then, only appear to 

 undergo transitions, when we have considered an organ or a' 

 property as invariable which is not so. 



