[100] Phil. Bot. p. 172.
[101] Ib. p. 171.
Again, the rule that the same parts are of very different value in different Orders, not only leaves us in want of rules or reasons which may enable us to compare the marks of different Orders, but destroys the systematic completeness of the natural arrangement. If some of the Orders be regulated by the flower and others by the fruit, we may have plants, of which the flower would place them in one Order, and the fruit in another. The answer to this difficulty is the maxim already stated;—that no Character makes the Order; and that if a Character do not enable us to recognize the Order, it does not answer its purpose, and ought to be changed for another.
This doctrine, that the Character is to be employed as a servant and not as a master, was a stumbling-block in the way of those disciples who looked only for dogmatical and universal rules. One of Linnæus’s pupils, Paul Dietrich Giseke, has given us a very lively account of his own perplexity on having this view propounded to him, and of the way in which he struggled with it. He had complained of the want of intelligible grounds, in the collection of natural orders given by Linnæus. Linnæus[102] wrote in answer, “You ask me for the characters of the Natural Orders: I confess I cannot give them.” Such a reply naturally increased Giseke’s difficulties. But afterwards, in 1771, he had the good fortune to spend some time at Upsal; and he narrates a conversation which he held with the great [399] teacher on this subject, and which I think may serve to show the nature of the difficulty;—one by no means easily removed, and by the general reader, not even readily comprehended with distinctness. Giseke began by conceiving that an Order must have that attribute from which its name is derived;—that the Umbellatæ must have their flower disposed in an umbel. The “mighty master” smiled,[103] and told him not to look at names, but at nature. “But” (said the pupil) “what is the use of the name, if it does not mean what it professes to mean?” “It is of small import” (replied Linnæus) “what you call the Order, if you take a proper series of plants and give it some name, which is clearly understood to apply to the plants which you have associated. In such cases as you refer to, I followed the logical rule, of borrowing a name a potiori, from the principal member. Can you” (he added) “give me the character of any single Order?” Giseke. “Surely, the character of the Umbellatæ is, that they have an umbel?” Linnæus. “Good; but there are plants which have an umbel, and are not of the Umbellatæ.” G. “I remember. We must therefore add, that they have two naked seeds.” L. “Then, Echinophora, which has only one seed, and Eryngium, which has not an umbel, will not be Umbellatæ; and yet they are of the Order.” G. “I would place Eryngium among the Aggregatæ. L. “No; both are beyond dispute Umbellatæ. Eryngium has an involucrum, five stamina, two pistils, &c. Try again for your Character.” G. “I would transfer such plants to the end of the Order, and make them form the transition to the next Order. Eryngium would connect the Umbellatæ with the Aggregatæ.” L. “Ah! my good friend, the Transition from Order to Order is one thing; the Character of an Order is another. The Transitions I could indicate; but a Character of a Natural Order is impossible. I will not give my reasons for the distribution of Natural Orders which I have published. You or some other person, after twenty or after fifty years, will discover them, and see I was in the right.”
[102] Linnæi Prælectiones, Pref. p. xv.
[103] “Subrisit ὁ πανυ.”
I have given a portion of this curious conversation in order to show that the attempt to establish Natural Orders leads to convictions which are out of the domain of the systematic grounds on which they profess to proceed. I believe the real state of the case to be that the systematist, in such instances, is guided by an unformed and undeveloped apprehension of physiological functions. The ideas of the form, [400] number, and figure of parts are, in some measure, overshadowed and superseded by the rising perception of organic and vital relations; and the philosopher who aims at a Natural Method, while he is endeavoring merely to explore the apartment in which he had placed himself, that of Arrangement, is led beyond it, to a point where another light begins, though dimly, to be seen; he is brought within the influence of the ideas of Organization and Life.
The sciences which depend on these ideas will be the subject of our consideration hereafter. But what has been said may perhaps serve to explain the acknowledged and inevitable imperfection of the unphysiological Linnæan attempts towards a natural method. “Artificial Glasses are,” Linnæus says, “a substitute for Natural, till Natural are detected.” But we have not yet a Natural Method. “Nor,” he says, in the conversation above cited, “can we have a Natural Method; for a Natural Method implies Natural Classes and Orders; and these Orders must have Characters.” “And they,” he adds in another place,[104] “who, though they cannot obtain a complete Natural Method, arrange plants according to the fragments of such a method, to the rejection of the Artificial, seem to me like persons who pull down a convenient vaulted room, and set about building another, though they cannot turn the vault which is to cover it.”
[104] Gen. Plant. in Prælect. p. xii.
How far these considerations deterred other persons from turning their main attention to a natural method, we shall shortly see; but in the mean time, we must complete the history of the Linnæan Reform.