Thus Oken postulated, as the specific vehicle of life, a primitive substance, in essence at least homogeneous. But he went further, and maintained that his 'Urschleim' assumed the form of vesicles, of which the various organisms were composed. 'The organic world has as its basis an infinitude of such vesicles.' Who is not at once reminded of the now dominant Cell-theory? And, in fact, thirty years later, when the cell was discovered, Oken did claim priority for himself. In so doing, he obviously confused the formulating of a problem with the solving of it; he had, quite rightly, divined that organisms must be built up of very minute concentrations of the primitive substance, but he had never seen a cell, or proved the necessity for its existence, or even attempted to prove it. His vesicle-theory was a pure divination, a prevision of genius, but one which could not directly deepen knowledge; it did not prompt, or even hasten, the discovery of the cell. Here, as throughout in his natural philosophy, Oken built, not from beneath upwards, by first establishing facts and then drawing conclusions from them, but, inversely, he invented ideas and principles, and out of them reconstructed the world. In this he differs essentially from his predecessors Erasmus Darwin, Treviranus, and Lamarck, who all reasoned inductively, that is, from observed data.
Thus the whole evolutionary movement was lost in indefiniteness; because men wanted to find a reason for everything, they missed even what might then have been explained. Moreover, the theory of evolution still lacked a sufficiently broad basis of facts; the 'Naturphilosophie,' by its want of moderation, robbed it of all credit; and it is not to be wondered at that men soon ceased to occupy themselves with the problem of the evolution of the living world. A few indeed held fast to the doctrine of evolution during the first third of the century, but then it disappeared completely from the realm of science.
Its last flicker of life was seen in France, in 1830, at the time of the July revolution, when the legitimate sovereignty of Charles X was overthrown. It is interesting to note the lively interest that Goethe, the first forerunner of the theory, and then aged eighty-one, had in the intellectual combat that took place in the French Academy between Cuvier and Isidore Geoffroy St.-Hilaire. A friend of Goethe's, Soret, relates that on August 2, 1830, he went into the poet's room, and was greeted with the words: 'Well, what do you think of this great event? The volcano is in eruption, and all is in flames. There can no longer be discussion with closed doors.' Soret replied: 'It is a terrible business! But what else was to be expected with things as they are, and with such a ministry, than that it should end in the expulsion of the reigning family?' To which Goethe answered: 'We don't seem to understand each other, my dear friend. I am not talking of these people at all; I am thinking of quite different affairs. I refer to the open rupture in the Academy between Cuvier and Geoffroy St.-Hilaire; it is of the utmost importance to science.'
In this conflict of opinions, Cuvier opposed Geoffroy's conception of the unity of the plan of structure in all animals, confronting him with the four Cuvierian types, in each of which the plan of structure was altogether different, and strongly insisting on the doctrine of the fixity of species, which he maintained to be the necessary postulate of a scientific natural history.
The victory fell to Cuvier, and it cannot be denied that there was much justification for his opinions at the time, for the knowledge of facts at that stage was not nearly comprehensive enough to give security to the Evolution theory, and moreover the quiet progress of science might have been hindered rather than furthered by premature generalization and theorizing. It had now been seen how far the interpretation of general biological problems could be carried with the available material; the 'Naturphilosophie' had not merely exploited it as far as possible, but had burdened it much beyond its carrying power, and the world was weary of insecure speculations. The 'Naturphilosophie' was for the time quite worked out, and a long period set in, during which all energies were devoted to detailed research.
LECTURE II
THE DARWINIAN THEORY
Period of detailed research—Appearance of Darwin's Origin of Species—Darwin's life—Voyage round the world—His teaching—Domesticated animals, dog, horse—Pigeons—Artificial selection—Unconscious selection—Correlated variations.