Dr, Lindley’s Natural System of Botany. 297 
And finally, their vascular system is very imperfect compared with 
that of other Exogens of an equal degree of development. 
The other group, called Rhizanthe, is far less correctly known, 
but it seems to stand as it were between Endogens and Acrogens” 
of the lowest grade ; agreeing with the latter in the absence or very 
imperfect state of the ni system, in a general resemblance to 
Fungi, and in the apparent seeds being mere masses of sporules ; 
but apparently according with Endogens in the. ternary number of 
their floral envelopes, and in the presence of fully developed sexes. 
“ Certainly there is no possibility of obtaining such important pri- 
mary groups as these by any kind of artificial contrivance.”—(Pre- 
Jace, p. X.—xii 
The grand ee divisions of the vegetable kingdom are, there- 
fore perfectly obvious, and may be very clearly defined. With our 
present knowledge of vegetable structure no great difliculty is expe- 
rienced in characterizing the orders or natural families, and all sub- 
ordinate groups. ‘The great desideratum has ever been to effect 
such an arrangement of the orders under the primary classes, that 
each family should be placed next to those which it most nearly re- 
sembles. This might easily be accomplished, if the idea once so 
strongly insisted upon by poets and metaphysicians, of a chain of 
beings, a regular gradation, by a single series, from the most perfect 
and complicated to the most simple forms of existence, had any 
foundation in truth. On the contrary, nothing is more evident, 
than that almost every order, or other group, is allied not merely to 
. One or two, but often to several others, which are sometimes widely 
separate from each other ; and, indeed, these several points of re- 
semblance or aflinity, are occasionally of about equal importance. 
A truly natural lineal arrangement is therefore impracticable, since 
by it only one or two out of several points of agreement can be indi- 
cated. As this method is, however, the only: one that can be fol- 
lowed in books, all that can be done is to arrange the orders in such 
a manner as to offer the least possible interruption to their natural 
affinities. ‘The number of orders is so large that practical conveni- 
ence seems to require their arrangement into groups subordinate to 
the primary classes; and when manifestly natural assemblages can- 
not be recognized, we are obliged to employ those which, being less 
strongly marked, and distinguished by a smaller number of charac- 
ters, are a. pparently of a more artificial nature. The arrangement 
ed by the learned Jussieu, in his celebrated Genera Planta- 
Vou. XXXII.—No. 2. 
