PHYSIOLOGICAL AND CLASSIFICATIONAL VALUE OF AN ORGAN TO COINCIDE! Just
as in Christian countries there is a catechismal morality, which every
one has upon his lips, but no one considers himself bound to follow, or
expects to see followed by anybody else, so also has Zoology its dogmas,
which are as universally acknowledged, as they are disregarded in
practice. Such a dogma as this is the supposition tacitly made by
Agassiz. Of a hundred who feel themselves compelled to give their
systematic confession of faith as the introduction to a Manual or
Monographic Memoir, ninety-nine will commence by saying that a natural
system cannot be founded upon a single character, but that it has to
take into account all characters, and the general structure of the
animal, but that we must not simply sum up these characters like
equivalent magnitudes, that we must not count but weigh them, and
determine the importance to be ascribed to each of them according to its
physiological significance. This is probably followed by a little jingle
of words in general terms on the comparative importance of animal and
vegetative organs, circulation, respiration, and the like. But when we
come to the work itself, to the discrimination and arrangement of the
species, genera, families, etc., in all probability not one of the
ninety-nine will pay the least attention to these fine rules, or
undertake the hopeless attempt to carry them out in detail. Agassiz, for
example, like Cuvier, and in opposition to the majority of the German
and English zoologists, regards the Radiata as one of the great primary
divisions of the Animal Kingdom, although no one knows anything about
the significance of the radiate arrangement in the life of these
animals, and notwithstanding that the radiate Echinodermata are produced
from bilateral larvae. The "true Fishes" are divided by him into
Ctenoids and Cycloids, according as the posterior margin of their scales
is denticulated or smooth, a circumstance the importance of which to the
animal must be infinitely small, in comparison to the peculiarities of