Candolle and Robert Brown. The former concentrated his
own long life and that of his son upon a new “systema naturae,”
the colossal Prodromus systematis naturalis (20 vols., 1818–1873),
in which 80,000 species were described and arranged. Meanwhile
the penetrative genius of Brown enabled him to unravel
such structural complexities as those of Conifers and Cycads,
Orchids and Proteaceae, thus demonstrating the possibility of
ascertaining the systematic position of even the most highly
modified floral types. Both Candolle and Brown were thus no mere
systematists, but genuine morphologists of the modern school.
The labours of Bernard and Antoine de Jussieu initiated a parallel advance in zoology, the joint memoir on the classification of mammals with which Cuvier and Geoffroy St-Hilaire almost began their career receiving its dominant impulse from the “genera” of Antoine. Cuvier’s works correspond in zoology to those of the whole period from the Jussieus to Brown, and epitomize the results of that line of advance. Although in some respects preceded by A. von Haller and J. Hunter, who compared, though mainly with physiological aim, the same parts in different organisms, and much more distinctly by Vicq d’ Azyr, the only real comparative anatomist of the 18th century, he opens the era of detailed anatomical research united with exact comparison and clear generalization. The Règne animal (1817) and the theory of types (vertebrate, molluscan, articulate, and radiate) are the results of this union of analysis and synthesis and mark the reconstitution of taxonomy on a new basis, henceforth to be no longer a matter of superficial description and nomenclature but a complete expression of structural resemblances and differences. In Germany, L. H. Bojanus, J. F. Meckel, C. T. E. von Siebold and Johannes Müller, with his many pupils, carried on the work; in France, too, a succession of brilliant anatomists, such as A. De Quatrefages, A. Milne-Edwards and H. de Lacaze-Duthiers, were his intellectual heirs; and in England he has been admirably represented by Sir R. Owen.
It is now necessary to return to Linnaeus, whose more speculative writings contain, though encumbered by fantastic hypotheses, the idea of floral metamorphosis. About the same time, and quite independently, C. F. Wolff, the embryologist, stated the same theory with greater clearness, for the first time distinctly reducing the plant to an axis bearing appendages—the vegetative leaves—which become metamorphosed into bud-scales or floral parts through diminution of vegetative force. Thirty years later the same view was again independently developed by Goethe in his now well-known pamphlet (Versuch die Metamorphose der Pflanzen zu erklären, Gotha, 1790). In this brilliant essay the doctrine of the fundamental unity of floral and foliar parts is clearly enunciated, and supported by arguments from anatomy, development and teratology. All the organs of a plant are thus modifications of one fundamental organ—the leaf—and all plants are in like manner to be viewed as modifications of a common type—the Urpflanze. Whether, as some historians hold, his “Urpflanze” was a mere ideal archetype, bringing forth as its fruit the innumerable metaphysical abstractions of the Naturphilosophie, and leading his countrymen into all the extravagances of that system; or whether, as E. H. Haeckel maintains, it represented a concrete ancestral form, so anticipating the view of modern evolutionists, it is certain that to him F. W. S. von Schelling was indebted for the foundation upon which he erected his philosophic edifice, as also that Goethe shared the same ideas. It must be remembered that he lived and made progress for forty years after the publication of this essay, that he was familiar with the whole scientific movement, and warmly sympathized with the evolutionary views of Lamarck and Geoffroy St-Hilaire; it is not therefore to be wondered at that his writings should furnish evidence in favour of each and every interpretation of them. His other morphological labours must not be forgotten. Independently of Vicq d’ Azyr, he discovered the human premaxillary bone; independently of L. Oken, he proposed the vertebral theory of the skull; and before S. C. Savigny, he discerned that the jaws of insects were the limbs of the head.
In 1813 A. P. de Candolle published his Théorie élémentaire de la botanique, which he developed into the classic Organographie végétale (1827). He established his theory of symmetry, reducing all flowers to “symmetrical” groupings of appendages on an axis and accounting for their various forms by cohesion and adhesion, by arrested or excessive development. The next advance was the investigation by W. P. Schimper and A. Braun of phyllotaxis—the ascending spiral arrangement of foliar and floral organs—thus further demonstrating their essential unity.
The term morphology was first introduced by Goethe in 1817, in a subsequent essay (Zur Naturwissenschaft überhaupt, besonders zur Morphologie). It did not come into use in botany until its popularization by Auguste de St-Hilaire in his Morphologie végétale (1841), and in zoology until later, although De Blainville, who also first employed the term type, had treated the external forms of animals under “morphologic.” Though the Naturphilosophie of Schelling and its countless modifications by his followers, its mystic theories of “polarization” and the like, its apparatus of assumption and abstraction, hypothesis and metaphor, cannot here be discussed, its undoubted services must not be forgotten, since it stimulated innumerable reflective minds to the earnest study of natural science, gave a powerful impulse to the study of comparative anatomy and vindicated the claims of philosophic synthesis over those of analytic empiricism. Among its many adherents, some are of more distinctly theological type; others metaphysical, others mystical or poetic, others, again, more especially scientific; but its most typical and picturesque figure is Lorenz Oken, who epitomizes alike the best and the worst features of the school, and among whose innumerable pseudo-morphological dreams there occasionally occurred suggestions of the greatest fruitfulness—notably, for instance, the independent statement of the vertebral theory of the skull.
By far the most distinguished anatomist of the transcendental school is Geoffroy St-Hilaire, who being comparatively free from the extravagances of Oken, and uniting a depth of morphological insight scarcely inferior to that of Goethe with greater knowledge of facts and far wider influence and reputation in the scientific world, had greater influence on the progress of science than either. He started from the same studies of anatomical detail as Cuvier, but, influenced by Buffon’s view of unity of plan and by the evolutionary doctrines of Lamarck, diverged into new lines, and again reached that idea of serial homology of which we have so frequently noted the independent origin. His greatest work, the Philosophie anatomique (1818–1823), contains his principal doctrines. These are: (1) the theory of unity of organic composition, identical in spirit with that of Goethe; (2) the theory of analogues, according to which the same parts, differing only in form and in degree of development, should occur in all animals; (3) the “principe des connexions,” by which similar parts occur everywhere in similar relative positions; and (4) the “principe du balancement des organes,” upon which he founded the study of teratology, and according to which the high development of one organ is allied to diminution of another. The advance in morphological theory is here obvious; unfortunately, however, in eager pursuit of often deceptive homologies, he wandered into the transcendentalism of the Naturphilosophie, and seems utterly to have failed to appreciate either the type theory of Cuvier or the discoveries of Von Baer. He defended Buffon’s and Bonnet’s earlier view of unity of plan in nature; and the controversy reached its climax in 1830, when he maintained the unity of structure in Cephalopods and Vertebrates against Cuvier before the Academy of Sciences. On the point of fact he was of course utterly defeated; the type theory was thenceforward fully accepted and the Naturphilosophie received its death-blow. Such was the popular view; only a few, like the aged Goethe, whose last literary effort was a masterly critique of the controversy, discerned that the very reverse interpretation was the deeper and essential one, that a veritable “scientific revolution” was in progress, and that the supremacy of homological and synthetic over descriptive and analytic studies was
