SPECIFIC CHARACTERS, 55 



practice, should give his days and nights to the sub- 

 ject. 



A Differentia Specified, Specific Character, or as 

 Linnaeus usually called it Nomen Specificum, should 

 comprehend such characters only as are requisite, or 

 sufficient, to distinguish a plant from every other spe- 

 cies of the same Genus. Such therefore is not a de- 

 scription, but a difference, and where only one Spe- 

 cies exists, a Differentia Specifica is an absurdity. If 

 it attempts to contrast the plant with the Species of 

 any other Genus, it is fallacious and erroneous. 



A Specific Character therefore is the essential pe- 

 culiarity of the full description, or complete idea, of 

 every plant, whether drawn out in detail, or existing 

 in the mind of the author. 



All accidental circumstances are necessarily to be 

 excluded, such as Country, Situation, Duration, Eco- 

 nomical Uses, the Name of the Discoverer, &c. 



All marks universally variable are also to be omitted, 

 among which are Colour, Smell, Taste, Size, Hairi- 

 nessin general, Curling of Leaves, Doubling of Flowers, 

 or any kind of Monstrosity. 



The direction of the hairs of Plants, as on the Ca- 

 lyx and Flowerstalk in Mentha and Myosotis, the 

 Stern of Papaver, and some other instances, not no- 

 ticed by Linnaeus, forms one exception to the above 

 rule ; and perhaps the presence cr absence of a glau- 

 cous hue in the herbage is another. 



Characters which presuppose any knowledge of 



