he has had upon the progress of Botany vouches for the correctness of his views.  Indeed, every profound scholar knows that sound learning can be attained only by this method, and the study of Nature makes no exception to the rule.  I would therefore advise every student to select a few representatives from all the Classes, and to study these not only with reference to their specific characters, but as members also of a Genus, of a Family, of an Order, of a Class, and of a Branch.  He will soon convince himself that Species have no more definite and real existence in Nature than all the other divisions of the Animal Kingdom, and that every animal is the representative of its Branch, Class, Order, Family, and Genus as much as of its Species, Specific characters are only those determining size, proportion, color, habits, and relations to surrounding circumstances and external objects.  How superficial, then, must be any one’s knowledge of an animal who studies it only with relation to its specific characters!  He will know nothing of the finish of special parts of the body,—­nothing of the relations between its form and its structure,—­nothing of the relative complication of its organization as compared with other allied animals,—­nothing of the general mode of execution,—­nothing of the plan expressed in that mode of execution.  Yet, with the exception of the ordinal characters, which, since they imply relative superiority and inferiority, require, of course, a number of specimens for comparison, his one animal would tell him all this as well as the specific characters.

All the more comprehensive groups, equally with Species, have a positive, permanent, specific principle, maintained generation after generation with all its essential characteristics.  Individuals are the transient representatives of all these organic principles, which certainly have an independent, immaterial existence, since they outlive the individuals that embody them, and are no less real after the generation that has represented them for a time has passed away than they were before.

From a comparison of a number of well-known Species belonging to a natural Genus, it is not difficult to ascertain what are essentially specific characters.  There is hardly among Mammalia a more natural Genus than that which includes the Rabbits and Hares, or that to which the Rats and Mice are referred.  Let us see how the different Species differ from one another.  Though we give two names in the vernacular to the Genus Hare, both Hares and Rabbits agree in all the structural peculiarities which constitute a Genus; but the different Species are distinguished by their absolute size when full-grown,—­by the nature and color of their fur,—­by the size and form of the ear,—­by the relative length of their legs and tail,—­by the more or less slender build of their whole body,—­by their habits, some living in open grounds, others among the bushes, others in swamps, others burrowing