Page:Popular Science Monthly Volume 2.djvu/329

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plied to physiological facts exclusively. This distinction is opposed to the tendencies of contemporaneous science, whose analyses reduce all morphological facts to physiological facts. Selection, Hartmann says, explains the progress in perfection of an already existing type, within its own degree of organization; but it cannot explain the passage from an inferior degree of organization to a superior one, a passage which always consists in an augmentation of the morphological type; and he gives, as a reason for his argument, that there is no more vitality in one morphological type than in another, and that selection is applicable only to facts that increase the vitality of the organism. All the degrees of organization possessing equal vitality, it is only, Hartmann insists, within the limits of a particular degree that different species or varieties are distinguished by more or less important advantages in the struggle for existence: if Darwinism were true of all species without restriction, there could only subsist one single morphological type in each locality, and, in the millions of years that the vital competition has lasted, all the inferior classes of animals and plants must have been extinguished by the superior classes; there are, in a word, a great number of facts which form part of the plan of the world, and yet are of no service in giving more vitality; such facts, in order to keep themselves in existence, need some other support than that of natural selection and the struggle for life.

We understand how many minds feel a certain repugnance in accepting the daring views of Darwin, so contrary to old associations of ideas. It is as yet nothing more than an hypothetic induction, which is waiting for its experimental verification. But it is no less true that this is the most probable of all the theories hitherto put forth upon the forms of life, and in default of that palpable and decisive demonstration that time only can furnish, we shall at least maintain that this opinion deserves to be preferred to all those still far more hypothetic doctrines which cannot dispense with a supernatural principle.

No doubt Darwinism does not succeed in explaining every thing. It has never assumed to account for the existence of forces, for the origin of those movements which are the source, and as it were the substance of life; it takes into view only their direction and the procedure of their organization. Putting aside the mysterious problem of being, it takes cognizance only of the methods of being. Is this saying that selection is only one of the means employed by a superior intelligence to govern the other forces of the world toward its ends? Nothing permits us to suppose that, for, on the contrary, the peculiarity of selection, in all the cases to which it applies, is to explain order without calling in the aid of intelligence, and as a necessary resultant of the reciprocal action of forces.

We think, with Hartmann, that Darwinism can explain only those facts that relate to the vitality of beings. But what fact is there in living Nature which can be regarded as indifferent from the point of