[108] Trapp’s Transl. of Stower’s Life of Linnæus, p. 314.
I have purposely confined myself to the history of the Linnæan system in the cases in which it is most easily applicable, omitting all consideration of more obscure and disputed kinds of vegetables, as ferns, mosses, fungi, lichens, sea-weeds, and the like. The nature and progress of a classificatory science, which it is our main purpose to bring into view, will best be understood by attending, in the first place, to the cases in which such a science has been pursued with the most decided success; and the advances which have been made in the knowledge of the more obscure vegetables, are, in fact, advances in artificial classification, only in as far as they are advances in natural classification, and in physiology.
To these subjects we now proceed. [404]
CHAPTER V.
Progress towards a Natural System of Botany.
WE have already said, that the formation of a Natural System of classification must result from a comparison of all the resemblances and differences of the things classed; but that, in acting upon this maxim, the naturalist is necessarily either guided by an obscure and instinctive feeling, which is, in fact, an undeveloped recognition of physiological relations, or else acknowledges physiology for his guide, though he is obliged to assume arbitrary rules in order to interpret its indications. Thus all Natural Classification of organized beings, either begins or soon ends in Physiology; and can never advance far without the aid of that science. Still, the progress of the Natural Method in botany went to such a length before it was grounded entirely on the anatomy of plants, that it will be proper, and I hope instructive, to attempt a sketch of it here.
As I have already had occasion to remark, the earlier systems of plants were natural; and they only ceased to be so, when it appeared that the problem of constructing a system admitted of a very useful solution, while the problem of devising a natural system remained insoluble. But many botanists did not so easily renounce the highest object of their science. In France, especially, a succession of extraordinary men labored at it with no inconsiderable success: and they were seconded by worthy fellow-laborers in Germany and elsewhere.
The precept of taking into account all the parts of plants according to their importance, may be applied according to arbitrary rules. We may, for instance, assume that the fruit is the most important part; or we may make a long list of parts, and look for agreement in the greatest possible number of these, in order to construct our natural orders. The former course was followed by Gærtner;[109] the latter by Adanson. Gærtner’s principles, deduced from the dissection of more than a thousand kinds of fruits,[110] exercised, in the sequel, a great and [405] permanent influence on the formation of natural classes. Adanson’s attempt, bold and ingenious, belonged, both in time and character, to a somewhat earlier stage of the subject.[111] Enthusiastic and laborious beyond belief but self-confident, and contemptuous of the labors of others, Michael Adanson had collected, during five years spent in Senegal, an enormous mass of knowledge and materials; and had formed plans for the systems which he conceived himself thus empowered to reach, far beyond the strength and the lot of man.[112] In his Families of Plants, however, all agree that his labors were of real value to the science. The method which he followed is thus described by his eloquent and philosophical eulogist.[113]
[109] De Fructibus et Seminibus Plantarum. Stuttg. 1788–1791.
[110] Sprengel, ii. 290.
[111] Familles des Plantes, 1763.