Mr. Woops on the British Species of Rosa. 171 
adopted on the same principle of exciting the attention of other 
observers. 
The drawing out into a table the specific characters of a ge- 
nus possesses a double advantage; it brings them to a test, by 
which the writer will inevitably discover if unfortunately some 
of his specific characters should be drawn up without inclu- 
ding any peculiarities to separate it from others, a fault of which 
even good botanical works afford too many examples ; and it is 
of great assistance to the future investigator, as it leads him 
step by step to the species which is the object of his examina- 
tion. But in order to accomplish this end, it is necessary that 
the characters which are most important and most permanent 
should occupy the first places: it is desirable that the arrange- 
ment of the table should of itself divide the genus into its most 
natural families. ‘lo combine these advantages is no easy task. 
To discover characters which shall be permanent, always ca- 
pable of clear description and determination, and which at the 
same time shall uniformly bring together the most similar plants, 
and separate those comparatively dissimilar, is perhaps beyond 
the power of the human mind. Mr. Brown's arrangement of 
Proteacee, in the tenth volume of the Society's Transactions, is 
an excellent specimen of what may be done in this way. La- 
marck and De Candolle in their analysis of the genus Rosa in the 
Flore Francaise, have proceeded on a similar notion, though they 
have adopted a much inferior form, and seem to have had no 
higher ambition than to assist in some degree the investigation of 
the species. Even in this they have effected very little; because 
in taking first the colour of the flower, then the snape of the fruit, 
and then the prickliness of the peduncle, they have adopted for 
their leading divisions characters which are very variable. The 
: z 2 yellow- 
