[112] Cuvier’s Eloge.
[113] Cuv. Eloges, tom. i. p. 282.
Considering each organ by itself, he formed, by pursuing its various modifications, a system of division, in which he arranged all known species according to that organ alone. Doing the same for another organ, and another, and so for many, he constructed a collection of systems of arrangement, each artificial,—each founded upon one assumed organ. The species which come together in all these systems are, of all, naturally the nearest to each other; those which are separated in a few of the systems, but contiguous in the greatest number, are naturally near to each other, though less near than the former; those which are separated in a greater number, are further removed from each other in nature; and they are the more removed, the fewer are the systems in which they are associated.
Thus, by this method, we obtain the means of estimating precisely the degree of natural affinity of all the species which our systems include, independent of a physiological knowledge of the influence of the organs. But the method has, Cuvier adds, the inconvenience of presupposing another kind of knowledge, which, though it belongs only to descriptive natural history, is no less difficult to obtain;—the knowledge, namely, of all species, and of all the organs of each. A single one neglected, may lead to relations the most false; and Adanson himself, in spite of the immense number of his observations, exemplifies this in some instances.
We may add, that in the division of the structure into organs, and in the estimation of the gradations of these in each artificial system, there is still room for arbitrary assumption.
In the mean time, the two Jussieus had presented to the world a “Natural Method,” which produced a stronger impression than the [406] “Universal Method” of Adanson. The first author of the system was Bernard de Jussieu, who applied it in the arrangement of the garden of the Trianon, in 1759, though he never published upon it. His nephew, Antoine Laurent de Jussieu, in his Treatise of the Arrangement of the Trianon,[114] gave an account of the principles and orders of his uncle, which he adopted when he succeeded him; and, at a later period, published his Genera Plantarum secundum Ordines Naturales disposita; a work, says Cuvier, which perhaps forms as important an epoch in the sciences of observation, as the Chimie of Lavoisier does in the sciences of experiment. The object of the Jussieus was to obtain a system which should be governed by the natural affinities of the plants, while, at the same time, the characters by which the orders were ostensibly determined, should be as clear, simple, and precise, as those of the best artificial system. The main points in these characters were the number of the cotyledons, and the structure of the seed: and subordinate to this, the insertion of the stamina, which they distinguished as epigynous, perigynous, and hypogynous, according as they were inserted over, about, or under, the germen. And the classes which were formed by the Jussieus, though they have since been modified by succeeding writers, have been so far retained by the most profound botanists, notwithstanding all the new care and new light which have been bestowed upon the subject, as to show that what was done at first, was a real and important step in the solution of the problem.
[114] Mém. Ac. P. 1774.
The merit of the formation of this natural method of plants must be divided between the two Jussieus. It has been common to speak of the nephew, Antoine Laurent, as only the publisher of his uncle’s work.[115] But this appears, from a recent statement,[116] to be highly unjust. Bernard left nothing in writing but the catalogues of the garden of the Trianon, which he had arranged according to his own views; but these catalogues consist merely of a series of names without explanation or reason added. The nephew, in 1773, undertook and executed for himself the examination of a natural family, the Ranunculaceæ; and he was wont to relate (as his son informs us) that it [407] was this employment which first opened his eyes and rendered him a botanist. In the memoir which he wrote, he explained fully the relative importance of the characters of plants, and the subordination of some to others;—an essential consideration, which Adanson’s scheme had failed to take account of. The uncle died in 1777; and his nephew, in speaking of him, compares his arrangement to the Ordines Naturales of Linnæus: “Both these authors,” he says, “have satisfied themselves with giving a catalogue of genera which approach each other in different points, without explaining the motives which induced them to place one order before another, or to arrange a genus under a certain order. These two arrangements may be conceived as problems which their authors have left for botanists to solve. Linnæus published his; that of M. de Jussieu is only known by the manuscript catalogues of the garden of the Trianon.”
[115] Prodromus Floræ Penins. Ind. Orient. Wight and Walker-Arnott, Introd. p. xxxv.
[116] By Adrien de Jussieu, son of Antoine Laurent, in the Annales des Sc. Nat., Nov. 1834.