In some families of the vegetable kingdom we can appreciate better the application of this nomenclature, because we have something corresponding to it in the vernacular.  We have, for instance, one name for all the Oaks, but we call the different kinds Swamp Oak, Red Oak, White Oak, Chestnut Oak, etc.  So Linnaeus, in his botanical nomenclature, called all the Oaks by the generic name Quercus, (characterizing them by their fruit, the acorn, common to all,) and qualified them as Quercus bicolor, Quercus rubra, Quercus alba, Quercus castanea, etc., etc.  His nomenclature, being so easy of application, became at once exceedingly popular and made him the great scientific legislator of his century.  He insisted on Latin names, because, if every naturalist should use his own language, it must lead to great confusion, and this Latin nomenclature of double significance was adopted by all.  Another advantage of this binominal Latin nomenclature consists in preventing the confusion frequently arising from the use of the same name to designate different animals in different parts of the world,—­as, for instance, the name of Robin, used in America to designate a bird of the Thrush family, entirely different from the Robin of the Old World,—­or of different names for the same animal, as Perch or Chogset or Burgall for our Cunner.  Nothing is more to be deprecated than an over-appreciation of technicalities, valuing the name more highly than the thing; but some knowledge of this nomenclature is necessary to every student of Nature.

The improvements in science thus far were chiefly verbal.  Cuvier now came forward and added a principle.  He showed that all animals are built upon a certain number of definite plans.  This momentous step, the significance of which is not yet appreciated to its full extent; for, had its importance been understood, the efforts of naturalists would have been directed toward a further illustration of the distinctive characteristics of all the plans,—­instead of which, the division of the animal kingdom into larger and smaller groups chiefly attracted their attention, and has been carried too far by some of them.  Linnaeus began with six classes, Cuvier brought them up to nineteen, and at last the animal kingdom was subdivided by subsequent investigators into twenty-eight classes.  This multiplication of divisions, however, soon suggested an important question:  How far are these divisions natural or inherent in the objects themselves, and not dependent on individual views?

While Linnaeus pointed out classes, orders, genera, and species, other naturalists had detected other divisions among animals, called families.  Lamarck, who had been a distinguished botanist before he began his study of the animal kingdom, brought to his zooelogical researches his previous methods of investigation.  Families in the vegetable kingdom had long been distinguished by French botanists; and one cannot examine the groups