No one expressed this objection with greater force than did von Baer, in a series of masterly essays[361] which the Darwinians, through sheer inability to grasp his point of view, dismissed as the maunderings of old age. In these essays von Baer pointed out the necessity for the teleological point of view, at least as complementary to the mechanistic. His general position is that of the "statical"
teleology--to use Driesch"s term--of Kant and Cuvier. His att.i.tude to Darwinism is determined by his teleology. He admits, just as in 1834, a limited amount of evolution; he criticises the evolution theory of Darwin on the same lines exactly as forty or fifty years previously he had criticised the recapitulation and evolution-theories of the transcendentalists--princ.i.p.ally on the ground that their deductions far outrun the positive facts at their disposal. He rejects the theory of natural selection entirely, on the ground that evolution, like development, must have an end or purpose (_Ziel_)--"A becoming without a purpose is in general unthinkable" (p. 231); he points out, too, the difficulty of explaining the correlation of parts upon the Darwinian hypothesis. His own conception of the evolutionary process is that it is essentially _zielstrebig_ or guided by final causes, that it is a true _evolutio_ or differentiation, just as individual development is an orderly progress from the general to the special. He believed in saltatory evolution, in polyphyletic descent, and in the greater plasticity of the organism in earlier times.
The idea of saltatory evolution he took from Kolliker, who shortly after the publication of the _Origin_ promulgated in a critical note on Darwinism a sketch of his theory of "heterogeneous generation."[362]
Kolliker"s att.i.tude is typical of that taken up by many of the morphologists of the day.[363] He accepts evolution completely, but rejects Darwinism because it recognises no _Entwickelungsgesetz_, or principle of evolution. For the Darwinian theory of evolution through the selection of small fortuitous variations he would subst.i.tute the theory of evolution through sudden, large variations, brought about by the influence of a general law of evolution. This is his theory of heterogeneous generation. "The fundamental idea of this hypothesis is that under the influence of a general law of evolution creatures produce from their germs others which differ from them" (p. 181). It is to be noticed that Kolliker laid more stress upon the _Entwickelungsgesetz_ than upon the saltatory nature of variation, for he says a few pages further on--"the notion at the base of my theory is that a great evolutionary plan underlies the development of the whole organised world, and urges on the simpler forms towards ever higher stages of complexity" (p. 184). Saltatory evolution was not the essential point of the theory:--"Another difference between the Darwinian hypothesis and mine is that I postulate many saltatory changes, but I will not and indeed cannot lay the chief stress upon this point, for I have not intended to maintain that the general law of evolution which I hold to be the cause of the creation of organisms, and which alone manifests itself in the activity of generation, cannot also so act that from one form others quite gradually arise" (p. 185). He put forward the hypothesis of saltatory variation because it seemed to him to lighten many of the difficulties of Darwinism--the lack of transition forms, the enormous time required for evolution, and so on. It should be noted that Kolliker regarded his principle of evolution as mechanical.
It would take too long to show in detail how a belief in innate laws of evolution was held by the majority of Darwin"s critics. A few further examples must suffice.
Richard Owen, who in 1868[364] admitted the possibility of evolution, held that "a purposive route of development and change, of correlation and interdependence, manifesting intelligent Will, is as determinable in the succession of races as in the development and organisation of the individual. Generations do not vary accidentally, in any and every direction; but in pre-ordained, definite, and correlated courses" (p.
808).
He conceived change to have taken place by abrupt variation, independent of environment and habit, by "departures from parental type, probably sudden and seemingly monstrous, but adapting the progeny inheriting such modifications to higher purposes" (p. 797). He believed spontaneous generation to be a phenomenon constantly taking place, and constantly giving the possibility of new lines of evolution.
E. von Hartmann in his _Philosophie des Unbewussten_ (1868) and in his valuable essay on _Wahrheit und Irrtum im Darwinismus_ (1874) criticised Darwinism in a most suggestive manner from the vitalistic standpoint. He drew attention to the importance of active adaptation, the necessity for a.s.suming definite and correlated variability, and to the evidence for the existence of an immanent, purposive, but unconscious principle of evolution, active as well in phylogenetic as in individual development.
In France H. Milne-Edwards[365] stated the problem thus:--"In the present state of science, ought we to attribute to modifications dependent on the action of known external agents the differences in the organic types manifested by the animals distributed over the surface of the globe either at the present day, or in past geological ages? Or must the origin of types transmissible by heredity be attributed to causes of another order, to forces whose effects are not apparent in the present state of things, to a creative power independent of the general properties of organisable matter such as we know them to-day?" (p. 426)
He concluded that the action of environment, direct or indirect, was insufficient to account for the diversity of organic forms, and rejected Darwin"s theory completely. He thought it likely that the successive faunas which palaeontology discloses have originated from one another by descent. But he thought that the process by which they evolved should rightly be called "creation." The word was of course not to be taken in a crude sense. When the zoologist speaks of the "creation" of a new species, "he in no way means that the latter has arisen from the dust, rather than from a pre-existing animal whose mode of organisation was different; he merely means that the known properties of matter, whether inert or organic, are insufficient to bring about such a result, and that the intervention of a hidden cause, of a power of some higher order, seems to him necessary" (p. 429).
The criticism of Darwinism exercised by the older currents of thought remained on the whole without influence. It was under the direct inspiration of the Darwinian theory that morphology developed during the next quarter of a century.
[333] Radl, _loc. cit._, i., p. 71.
[334] _Kritik der Urtheilskraft_, 1790.
[335] Eng. Trans. by J. H. Bernard, p. 337, London, 1892.
[336] H. F. Osborn, _From the Greeks to Darwin_, p. 145, New York and London, 1894.
[337] See Meckel, _supra_, p. 93; _cf._ Tiedemann, _Zoologie_, p. 65, 1808. "Even as each individual organism transforms itself, so the whole animal kingdom is to be thought of as an organism in course of metamorphosis." Also p. 73 of the same book.
[338] Chapters vii. and ix.
[339] On early evolution-theories see, in addition to Osborn and Radl, J. Arthur Thomson, _The Science of Life_, 1899, and the opening essay in _Darwin and Modern Science_, Cambridge, 1909.
[340] _Phil. zool._, ed. Ch. Martins, vol. i., p. 75, 1873.
[341] Quotations in the text are from the 2nd Edit.
(Deshayes and Milne-Edwards), i., Paris, 1835.
[342] For instance, Lucretius:--
"Is tibi nunc animus quali sit corpore et unde const.i.terit pergam rationem reddere dictis. Principio esse aio persubtilem atque minutis perquam corporibus factum constare."
--_De Rerum Natura_, iii., vv. 177-80.
[343] Contrast Trevira.n.u.s--"In every living being there exists a capability of an endless variety of form-a.s.sumption; each possesses the power to adapt its organisation to the changes of the outer world, and it is this power, put into action by the change of the universe, that has raised the simple zoophytes of the primitive world to continually higher stages of organisation, and has introduced a countless variety of species into animate Nature." Quoted by Haeckel in _History of Creation_, i., p. 93, 1876.
[344] There is no evidence that he was influenced by Erasmus Darwin, who forestalled his evolution theory, and was indeed more aware of its vitalistic implications. See S. Butler, _Evolution, Old and New_, London, 1879, for an excellent account of Erasmus Darwin.
[345] As did also Lyell in his _Principles of Geology_, 1830.
[346] K. E. von Baer, _Reden_, i., p. 37, Petrograd, 1864.
[347] Radl, _loc. cit._, i., p. 296.
[348] Reprinted in his _Reden_, i., 1864.
[349] See Huxley"s criticism of it in a Royal Inst.i.tution lecture of 1851, republished in _Sci. Mem._, i., pp.
300-4. On its relation to Haeckel"s biogenetic law, see below, p. 255.
[350] _System der thierischen Morphologie_, p. 5, 1853.
[351] _Life and Letters of Charles Darwin_, ed. F. Darwin, i., p. 82, 3rd ed., 1887.
[352] _The Foundations of the Origin of Species, a Sketch written in 1842_. Ed. F. Darwin, Cambridge, 1909.
[353] _Cf._ a parallel pa.s.sage in the _Origin_, 1st ed., pp. 485-6.
[354] In the 1st ed. (p. 439), Darwin makes the curious mistake of attributing this story to Aga.s.siz.
[355] In which nestlings of the different varieties are much more alike than adults. Darwin attached much importance to this idea, see _Life and Letters_, i., p.
88, and ii., p. 338.
[356] See his _Letters, pa.s.sim_.
[357] Writing to Huxley on the subject of the latter"s work on the morphology of the Mollusca (1853), he says:--"The discovery of the type or "idea" (in your sense, for I detest the word as used by Owen, Aga.s.siz & Co.) of each great cla.s.s, I cannot doubt, is one of the very highest ends of Natural History."--_More Letters_, ed. F. Darwin and A. C. Seward, 1903, i., p. 73.
[358] Italics mine.
[359] _Das Problem des Lebens. Biologische Studien_. Bad Sacha, 1906. See also E. Radl, _Biol. Centralblatt_, xxi., 1901.
[360] See the excellent treatment of the difference between the "realism" of Darwin and the "rationalism" of his critics, in Radl, ii., particularly pp. 109, 135.
The most elaborate criticism of Darwinism from the older standpoint was that given by A. Wigand in _Der Darwinismus und die Naturforschung Newtons und Cuviers_, 3 vols., Braunschweig, 1872.
[361] In vol. ii. of his _Reden_, St Petersburg (Petrograd), 1876--_Ueber den Zweck in den Vorgangen der Natur; Ueber Zielstrebigkeit in den organischen Korpern insbesondere_; and _Ueber Darwin"s Lehre_.
[362] "Ueber die Darwinische Schopfungstheorie," _Zeits.
f. wiss. Zool._, xiv., pp. 74-86, 1864. Elaborated in _Anat. u. syst. Beschreibung d. Alcyonarien_, 1872.
[363] _Cf._ for instance Nageli"s theory of a perfecting principle, first developed in his _Entstehung u. Begriff der naturhistorischer Art_, Munchen, 1865.
[364] _Anatomy of Vertebrates_, iii., 1868.
[365] _Rapport sur les Progres recents des Sciences zoologiques en France_. Paris, 1867.