According to Linnæus’ plan, the more general and comprehensive generic name is written first; the special subordinate name of the species follows it. Thus, for example, the common cat is called Felis domestica; the wild cat, Felis catus; the panther, Felis pardus; the jaguar, Felis onca; the tiger, Felis tigris; the lion, Felis leo. All these six kinds of animals of prey are different species of one and the same genus—Felis. Or, to add an example from the vegetable kingdom, according to Linnæus’ designation the pine is Pinus abies; the fir, Pinus picea; the larch, Pinus larix; the Italian pine, Pinus pinea; the Siberian stone pine, Pinus cembra; the knee timber, Pinus mughus; the common pine, Pinus silvestris. All these seven kinds of pines are different species of one and the same genus—Pinus.
Perhaps this advance made by Linnæus may seem to some only of subordinate importance in the practical distinction and designation of the variously formed organisms. But in reality it was of the very greatest importance, both from a practical and theoretical point of view. For now, for the first time, it became possible to arrange the immense mass of different organic forms according to their greater or less degree of resemblance, and to obtain an easy survey of the general outlines of such a “system.” Linnæus facilitated the tabulation and survey of this “system” of plants and animals still more by placing together the most nearly similar genera into so-called orders (ordines); and by uniting the most nearly similar orders into still more comprehensive main divisions or classes. Thus, according to Linnæus, each of the two organic kingdoms were broken up into a number of classes, the vegetable kingdom into twenty-four, and the animal kingdom into six. Each class again contains several orders. Every single order may contain a number of genera, and, again, every single genus several species.
Valuable as was Linnæus’ binary nomenclature in a practical way, in bringing about a comprehensive systematic distinction, designation, arrangement, and division of the organic world of forms, yet the incalculable theoretical influence which it gained forthwith in relation to the history of creation was no less important. Even now all the important fundamental questions as to the history of creation turn finally upon the decision of the very remote and unimportant question, What really are kinds or species? Even now the idea of organic species may be termed the central point of the whole question of creation, the disputed centre, about the different conceptions of which Darwinists and Anti-Darwinists fight.
According to Darwin’s opinion, and that of his adherents, the different species of one and the same genus of animals and plants are nothing else than differently developed descendants of one and the same original primary form. The different kinds of pine mentioned above would accordingly have originated from a single primæval form of pine. In like manner the origin of all the species of cat mentioned above would be traced to a single common form of Felis, the ancestor of the whole genus. But further, in accordance with the Doctrine of Descent, all the different genera of one and the same order ought also to be descended from one common primary ancestor, and so, in like manner, all orders of a class from a single primary form.
On the other hand, according to the idea of Darwin’s opponents, all species of animals and plants are quite independent of each other, and only the individuals of each species have originated from a single primary form. But if we ask them how they conceive these original primary forms of each species to have come into existence, they answer with a leap into the incomprehensible, “They were created.”
Linnæus himself defined the idea of species in this manner by saying, “There are as many different species as there were different forms created in the beginning by the infinite Being.” (“Species tot sunt diversæ, quot diversas formas ab initio creavit infinitum ens.”) In this respect, therefore, he follows most closely the Mosaic history of creation, which in the same way maintains that animals and plants were created “each one after its kind.” Linnæus, accepting this, held that originally of each species of animals and plants either a single individual or a pair had been created; in fact a pair, or, as Moses says, “a male and a female” of those species which have separate sexes, but of those species in which each individual combines both sexual organs (hermaphrodites), as for instance the earthworm, the garden and vineyard snails, as well as the great majority of plants, a single individual.
Linnæus further follows the Mosaic legend in regard to the flood, by supposing that the great general flood destroyed all existing organisms, except those few individuals of each species (seven pairs of the birds and of clean animals, one pair of unclean animals) which Noah saved in the ark, and which were placed again on land, on Mount Ararat, after the flood had subsided. He tried to explain the geographical difficulty of the living together of the most different animals and plants, as follows: Mount Ararat, in Armenia, being situated in a warm climate, and rising over 16,000 feet in height, combines in itself the conditions for a temporary common abode of such animals as live in different zones. Accordingly, animals accustomed to the polar regions could climb up the cold mountain ridges, those accustomed to a warm climate could go down to the foot of the mountain, and the inhabitants of a temperate zone could remain midway up the mountain. From this point it was possible for them to spread north and south over the earth.
It is scarcely necessary to remark that this Linnæan hypothesis of creation, which evidently was intended to harmonize most closely with the prevailing belief in the Bible, requires no serious refutation. When we consider Linnæus’ clearness and sagacity in other matters, we may doubt whether he believed it himself. As to the simultaneous origin of all individuals of each species from one pair of ancestors respectively (or in the case of the hermaphrodite species, from one original hermaphrodite), it is clearly quite untenable; for, apart from other reasons, in the first days after the creation, the few animals of prey would have sufficed to have utterly demolished all the herbivorous animals, as the herbivorous animals must have destroyed the few individuals of the different species of plants. The existence of such an equilibrium in the economy of nature as obtains at present cannot possibly be conceived, if only one individual of each species, or only one pair, had originally and simultaneously been created.
Moreover, how little importance Linnæus himself attached to this untenable hypothesis of creation is clear, among other things, from the fact that he recognized Hybridism (crossing) as a source of the production of new species. He assumed that a great number of independent new species had originated by the interbreeding of two different species. Indeed, such hybrids are not at all rare in nature, and it is now proved that a great number of species, for example, of the genus Rubus (bramble), mullen (Verbascum), willow (Salix), thistle (Cirsium), are hybrids of different species of these genera. We also know of hybrids between hares and rabbits (two species of the genus Lepus), further of hybrids between different species of dog (genus Canis), etc., which can be propagated as independent species.
It is certainly very remarkable that Linnæus asserted the physiological (therefore mechanical) origin of new species in this process of hybridism. It clearly stands in direct opposition to the supernatural origin of the other species by creation, which he accepted as put forward in the Mosaic account. The one set of species would therefore have originated by dualistic (teleological) creation, the other by monistic (mechanical) development.