IN NATURAL CLASSIFICATION. 581 
hension, in the ratio of the importance of the characters 
by which they are joined. 
Let us suppose a group A united by a character of primary importance, 
and A divided into B and C by characters of secondary value; then B 
will contain the primary characters of A together with its own secondary 
characters, and C will contain the characters of A as well as its own 
secondary characters; so B and C, while less in extension than A, will 
exceed it in comprehension. For if B be equal in extension to A, then its 
secondary characters will be equal in extension to its primary, which is 
contrary to the last postulate, 
From this proposition flows the following corollary :—Groups of greater 
comprehension are subordinate ze or contained within groups of greater exten- 
sion. Another corollary is this :—Different groups possess affinities towards 
each other, in the ratio of the ls extension and greater comprehension of the 
group to which they are subordinate. Another corollary is Meas the cha- 
racters which unite small groups, and separate them fi i 
co-exist, with a great number of affinities. And las asds giu may Ze? by 
the considerable increase of mutual affinities, of the proper application of a 
character to the segregation of a small group. 
PnoBLEw.—'To arrange vegetables in groups, composed of 
elements having a greater number of constant resemblances 
amongst themselves than exist between them and the mem- 
bers of other groups: and to place these groups in relations 
more or less approached in the ratio of their mutual af- 
finities, 
Collect together all those plants that agree in characters of 
the highest value; sub-divide these by characters the nextin im- 
portance ; and again and again sub-divide these latter groups, 
according to the same principle, as long as characters can be 
found, whose application co-exists with an increasing multi- 
plication of affinities ; then permit the larger groups to ap- 
proximate, at those minor groups whose segregation is found- 
ed on similar characters. s 
By uniting together those plants that agree in the most essential cha- 
Tàcters, we form, according to the first Proposition, a group possessing 
Constant relations in less essential characters, and by Proposition 2nd, we 
have before ascertained that a classification founded on the organs of re- 
Production, is identical with one founded on the organs of nutrition. By 
the corollaries of the 3rd Proposition we have learned that groups of 
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