of the Grasses.
Numerous instances could be given of characters derived from parts
which must be considered of very trifling physiological importance, but
which are universally admitted as highly serviceable in the definition
of whole groups. For instance, whether or not there is an open passage
from the nostrils to the mouth, the only character, according to Owen,
which absolutely distinguishes fishes and reptiles the inflection of
the angle of the jaws in Marsupials the manner in which the wings of
insects are folded mere colour in certain Alg mere pubescence on parts
of the flower in grasses the nature of the dermal covering, as hair or
feathers, in the Vertebrata. If the Ornithorhynchus had been covered
with feathers instead of hair, this external and trifling character
would, I think, have been considered by naturalists as important an aid
in determining the degree of affinity of this strange creature to
birds and reptiles, as an approach in structure in any one internal and
important organ.
The importance, for classification, of trifling characters, mainly
depends on their being correlated with several other characters of more
or less importance. The value indeed of an aggregate of characters is
very evident in natural history. Hence, as has often been remarked, a
species may depart from its allies in several characters, both of high
physiological importance and of almost universal prevalence, and yet
leave us in no doubt where it should be ranked. Hence, also, it has
been found, that a classification founded on any single character,
however important that may be, has always failed; for no part of the
organisation is universally constant. The importance of an aggregate of
characters, even when none are important, alone explains, I think, that
saying of Linn us, that the characters do not give the genus, but the
genus gives the characters; for this saying seems founded on an
appreciation of many trifling points of resemblance, too slight to be
defined. Certain plants, belonging to the Malpighiace , bear perfect
and degraded flowers; in the latter, as A. de Jussieu has remarked,
the greater number of the characters proper to the species, to the
genus, to the family, to the class, disappear, and thus laugh at our
classification. But when Aspicarpa produced in France, during several
years, only degraded flowers, departing so wonderfully in a number of
the most important points of structure from the proper type of the
order, yet M. Richard sagaciously saw, as Jussieu observes, that this
312