BOTANICAL APHORISMS. 195 
root is under ground, that the leaves are green, &c. 
The old botanists frequently err in this respect. 
§ 196. 
The essential difference, or name, (diagnosis), of 
the species is a short description containing only 
what is essential; according to the following rules. | 
The specific name must not be too long, and if pos- 
sible should be contained in twelve words. 
We have seen, (§ 193), that in forming the spe- 
cific name we must express only the essential differ. 
ence, and so characterise it, that he who sees the 
plant for the first time, though he has never seen 
the other species of the genus, may be at no loss 
to know what plant he has before him. Words 
that are superfluous, must be omitted, and only 
those made use of which distinguish the plant from 
all others. If more than twelve words are neces- 
sary for the complete denomination of the plant, 
they must be adopted: for it is better that the name 
be long and distinct, than short and unintelligible. 
The specific name must be in the Latin language, and 
all the words in the ablative case. | 
We shall here recur to our old example, the 
Solanum tuberosum, the difference between which 
and the other numerous species of the genus is ex- 
pressed as follows. 
SOLANUM tuberosum; caule inermi herbaceo, foliis 
pinnatis integerrimis, pedunculis subdivisis. 
In the specific name there must be no relative idea. 
What was formerly said with regard to the dis- 
tinguishing of the species is applicable here. Mag- 
nitude, 
