and not even for the sake of its usefulness to humanity, that the
scientific man studies Nature. The application of science to the useful
arts requires other abilities, other qualities, other tools than his; and
therefore I say that the man of science who follows his studies into their
practical application is false to his calling. The practical man stands
ever ready to take up the work where the scientific man leaves it, and to
adapt it to the material wants and uses of daily life.

The publication of Cuvier's proposition, that the animal kingdom is built
on four plans, created an extraordinary excitement throughout the
scientific world. All naturalists proceeded to test it, and many soon
recognized in it a great scientific truth,--while others, who thought more
of making themselves prominent than of advancing science, proposed poor
amendments, that were sure to be rejected on farther investigation. There
were, however, some of these criticisms and additions that were truly
improvements, and touched upon points overlooked by Cuvier. Blainville,
especially, took up the element of form among animals,--whether divided on
two sides, whether radiated, whether irregular, etc. He, however, made the
mistake of giving very elaborate names to animals already known under
simpler ones. Why, for instance, call all animals with parts radiating in
every direction _Actinomorpha_ or _Actinozoaria_, when they had received
the significant name of _Radiates_? It seemed, to be a new system, when in
fact it was only a new name. Ehrenberg, likewise, made an important
distinction, when he united the animals according to the difference in
their nervous systems; but he also incumbered the nomenclature
unnecessarily, when he added to the names _Anaima_ and _Enaima_ of
Aristotle those of _Myeloneura_ and _Ganglioneura_.

But it is not my object to give all the classifications of different
authors here, and I will therefore pass over many noted ones, as those of