298 Dr. Lindley’s Natural System of Botany. 
rum, although to a considerable extent artificial, has been almost 
universally adopted, until within the last few years. 
In this method Dicotyledonous plants are primarily divided into 
three groups; the first including those with a polypetalous corolla; 
the second, those with a monopetalous corolla; and the third, those 
destitute of a corolla. These sections are subdivided, (as also the 
monocotyledons) by means of characters taken from the insertion of 
the stamens (or corolla,) whether hy pogynous, perigynous, or epigy- 
nous. ‘The arrangement here pursued, which is too well known to 
require further notice, is substantially adopted by De Candolle, the 
difference being more in appearance than reality. Dr. Lindley 
discarded these subdivisions in the first edition of his work; but the 
new distribution of the orders therein proposed possesses few advan- 
tages, and, indeed appears not to have satisfied the author himself. 
In the same year with the publication of the work just mentioned, 
the Ordines Plantarum of Bartling appeared, in which a more nat- 
ural arrangement of the orders is attempted by the formation of ag- 
gregate or compound orders, as originally proposed, and in several 
instances successfully accomplished, by Robert Brown. An analo- 
gous plan was pursued by Agardh in his Aphorismi Botanici, (1817,) 
and again in his Classes Plantarum, (1825;) but these attempts, 
however ingenious, do not seem to have obviated, in any considera- 
ble degree, the inconveniences of a lineal arrangement. 
We now return to our author, whose views upon this subject have 
been materially modified since the original publication of his Intro- 
duction to the Natural System. The method now employed was 
first sketched in the Nizus Plantarum, (1832,) and afterwards in - 
the Key to Structural, Physiological, and Systematic Botany,* 
(1835,) and is more fully developed and illustrated in the work 
before us. He now admits, as we have already seen, five primary 
classes, two of which, however, are much smaller than the others 
and of subordinate importance, and may be considered as transition 
classes, viz. Gymnosperme, which connect Exogens with the higher 
Acrogens, and Rhizanthe, which form the transition from Endogens 
to Acrogens of the lowest grade. The great class Exogene (Di- 
Saleen of Jussieu,) is divided into three subclasses, viz. 
* This excellent little work consists of an augmented edition of the author's 
Ouaine of the first principles of Botany, with a revised translation of the Nizus 
