580 ON THE USE OF POLLEN 
of existence require a constant relation between characters the most essen- 
tial and those less essential in an apparatus. w: 
e less essential characters in an apparatus have a constant relation 
to the most essential ; 
e most essential characters in a b c d (different vegetables) are iden- 
Pise the less essential characters in a b c d must have a con- 
stant relation to each other; therefore, a reunion of similar appa- 
ratusses agreeing in most essential characters, must be a reunion of 
apparatusses, having a constant relation in less essential cha- 
ract 
2nd.—A classification based on the reunion of apparatusses 
engaged in the performance of one function, is identical 
with a classification founded on the reunion of apparatus- 
ses engaged in the performance of another function. 
The proof of this depends on the last proposition, and on a postulate 
which we have already admitted; for if there be a constant relation be- 
tween characters equally essential in different apparatusses in the same 
individual; and if a reunion of similar apparatusses agreeing in the most 
essential CSS be a reunion of apparatusses having a constant rela- 
tion in less essential characters, there must be a constant relation between 
we suppose a classification founded on apparatus A, to be not identical 
with a classification founded on apparatus B, then either of these alterna- 
tives must be true; viz. that there is no constant relation or co-existence 
between any characters in ute apparatus, which is contrary to the postu- 
te ; or, that some characters may have a constant relation and others not, 
whack is contrary to the See: Therefore, these two classifications 
must be identical. 
Thus, according to the latter proposti. a classification founded on the 
organs of reproduction, is identical with a classification founded on the organs 
of nutrition. 
We require for our argument another postulate ; let it be 
granted that characters have a greater extension in the direct 
ratio of their importance. 
Thus, the existence of an embryo is more extensive than the presence of 
two cotyledons; the latter character is found in a greater number of spe- 
cies than the occurrence of a double perianth; and so forth. 
3rd.—Groups formed by the combination of similar cha- 
racters, will be greater in extension, and less in compre- 
