414 ARTIFICIAL SYSTEMS OF CLASSIFICATION. 
1670. He divided plants into eighteen classes, which were con- 
structed according io the nature of the flower and fruit, and the 
external appearance of the plants. The systems of Hermann and 
others were also constructed upon somewhat similar principles, 
while that of Camellus was framed from the characters presented 
by the valves of the pericarp, and their number. In the system 
of Rivinus, which was promulgated in the year 1690, plants were 
divided into eighteen classes ; these were founded entirely upon 
the corolla—its regularity or irregularity,.and the number of its 
parts being taken into consideration. The system of Christian 
Knaut was but a slight alteration of that of Rivinus. That of 
Tournefort, which was promulgated about the year 195, was for 
a considerable time the favourite system of all botanists. About 
8,000 species of plants were then known, which were distributed 
by Tournefort into twenty-two classes. He first arranged plants 
in two divisions, one of which comprised herbs and wnder-shrubs, 
and the other trees and shrubs ; and each of these divisions was 
then divided into classes, which were chiefly characterised ac- 
cording to the form of the corolla. Many other systems were 
devised which were simply alterations of the foregoing, as that 
of Pontedera. Magnolius, however, framed a system entirely 
on the calyx ; while Gleditsch attempted one in which the classes 
were founded on the position of the stamens. All the above 
systems were, without doubt, useful in their day, and paved the 
way for the more comprehensive one of Linnzeus, which we now 
proceed to notice. ; 
LinnazAN SystemM.—This celebrated system was first pro- 
mulgated by Linneeus in his ‘Systema Nature,’ published in 
the year 1735; and although it was somewhat altered by subse- 
quent botanists, the Linnzean System, in all its essential charac- 
ters, was that devised by Linnzeus himself; and although now 
superseded by natural systems, it will be advisable for us to give 
a general.sketch of its principal characteristics. 
The classes and orders in the Linnzean System are taken ex- 
clusively from the essential organs of reproduction, the sexual 
nature of which Linneeus had clearly established: hence this 
artificial scheme is commonly termed the Sexual System. 
The table (pp. 412 and 413) of the Classes and Orders of the 
Linnzan System. will show at a glance their distinctive cha- 
racteristics so far as the Phanerogamia are concerned ; but the 
Cryptogamia have been arranged according to the Natural 
System. 
Section 2, NATURAL SYSTEMS OF CLASSIFICATION. 
THe object of all natural systems, as already noticed (page 
411), is to group together those plants which correspond in the 
greatest number of important characters, and to separate those 
that are unlike. The mode in which this has been attempted 
