creation of single species could have held its ground up to the present day. It is only owing to his great authority, and through his attaching himself to the prevailing Biblical belief, that his hypothesis of creation has retained its position so long.

CHAPTER III.

THE HISTORY OF CREATION ACCORDING TO CUVIER AND AGASSIZ.

General Theoretical Meaning of the Idea of Species.-Distinction between the Theoretical and Practical Definition of the Idea of Species.-Cuvier's Definition of Species.-Merits of Cuvier as the Founder of Comparative Anatomy.-Distinction of the Four Principal Forms (types or branches) of the Animal Kingdom, by Cuvier and Bär.-Cuvier's Services to Palæontology. His Hypothesis of the Revolutions of our Globe, and the Epochs of Creation separated by them.-Unknown Supernatural Causes of the Revolutions, and the subsequent New Creations.-Agassiz's Teleological System of Nature.-His Conception of the Plan of Creation, and its six Categories (groups in classification).—Agassiz's Views of the Creation of Species.-Rude Conception of the Creator as a man-like being in Agassiz's Hypothesis of Creation.-Its internal Inconsistency and Contradictions with the important Palæontological Laws discovered by Agassiz.

THE real matter of dissension in the contest carried on by naturalists as to the origin of organisms, their creation and development, lies in the conceptions which are entertained about the nature of species. Naturalists either agree with Linnæus, and look upon the different species as distinct forms of creation, independent of one another, or they assume with Darwin their blood-relationship. If we share Linnæus' view (which was discussed in our last chapter), that the different organic species came into existence

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independently—that they have no blood-relationship—we are forced to admit a supernatural creation, and must either suppose that every single organic individual was a special act of creation (to which surely no naturalist will agree), or we must derive all individuals of every species from a single individual, or from a single pair, which did not arise in a natural manner, but was called into being by command of a Creator. In so doing, however, we turn aside from the safe domain of a rational knowledge of nature, and take refuge in the mythological belief in miracles.

If, on the other hand, with Darwin, we refer the similarity of form of the different species to real blood-relationship, we must consider all the different species of animals and plants as the altered descendants of one or a few most simple original forms. Viewed in this way, the Natural System of organisms (that is, their tree-like and branching arrangement and division into classes, orders, families, genera, and species) acquires the significance of a real genealogical tree, whose root is formed by those original archaic forms which have long since disappeared. But a truly natural and consistent view of organisms can assume no supernatural act of creation for even those simplest original forms, but only a coming into existence by spontaneous generation (archigony, or generatio spontanea). From Darwin's view of the nature of species, we arrive therefore at a natural theory of development; but from Linnæus' conception of the idea of species, we must assume a supernatural dogma of creation.

*

Most naturalists after Linnæus, whose great services in * Archebiosis (Bastian), Abiogenesis (Huxley).

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systematic and descriptive natural history won for him such high authority, followed in his footsteps, and without further inquiry into the origin of organization, they assumed, in the sense of Linnæus, an independent creation of individual species, in conformity with the Mosaic account of creation. The foundation of their conception was based upon Linnæus' words, "There are as many different species as there were different forms created in the beginning by the Infinite Being." We must here remark at once, without going further into the definition of species, that all zoologists and botanists in their classificatory systems, in the practical distinction and designation of species of animals and plants, never troubled, or even could trouble, themselves in the slightest degree about this assumed creation of the parentforms. In reference to this, one of our first zoologists, the ingenious Fritz Müller, makes the following striking observation: "Just as in Christian countries there is a catechism of morals, which every one knows by heart, but which no one considers it his duty to follow, or expects to see followed by others,-so zoology also has its dogmas, which are just as generally professed as they are denied in practice," ("Für Darwin," p. 71). 16

Linnæus' venerated dogma of species, up to quite recent times, was just such an irrational dogma, and indeed for that very reason most powerful. Although most naturalists blindly submitted to it, yet they were, of course, never in a position to demonstrate the descent of individuals belonging to one species from the common, originally created, primitive form. Zoologists and botanists, in their systems of nomenclature, confined themselves entirely to the similarity of forms, in order to distinguish and name the different species.

They placed in one species all organic individuals which were very similar, or almost identical in form, and which could only be distinguished from one another by very unimportant differences. On the other hand, they considered as different species those individuals which presented more essential or more striking differences in the formation of their bodies. But of course this opened the flood-gates to the most arbitrary proceedings in the systematic distinctions of species. For as all the individuals of one species are never completely alike in all their parts, but as every species varies more or less, no one could point out which degree of variation constituted a really "good species," or which degree indicated a "mere variety."

This dogmatic conception of the idea of species, and the arbitrary proceedings connected with it, necessarily led to the most perplexing contradictions, and to the most untenable suppositions. This is clearly demonstrable in the case of the celebrated George Cuvier (born in 1769), who next to Linnæus has exercised the greatest influence on the study of zoology. In his conception and definition of the idea of species, he agreed on the whole with Linnæus, and shared also his belief in an independent creation of individual species. Cuvier considered their immutability of such importance that he was led to the foolish assertion, "The immutability of species is a necessary condition of the existence of scientific natural history." As Linnæus' definition of species did not satisfy him, he made an attempt to give a more exact and, for systematic practice, a more useful definition, in the following words: "All those individual animals and plants belong to one species which can be proved to be either descended from one another, or from