History of scientific ideas

by William Whewell

[39] Hooker, Fl. Scot. 228.

Attempts have been made at various times to form the name of species from those of genera in some more symmetrical manner. Thus some have numbered the species of genus, 1, 2, 3, &c.; but this method is liable to the inconveniences, first, that it offers nothing for the memory to take hold of; and second, that if a new species intermediate between 1 and 2, 2 and 3, &c., be discovered, it cannot be put in its place. It has also been proposed to mark the species by altering the termination of the genus. Thus Adanson[40], denoting a genus by the name Fonna (Lychnidea), conceived he might mark five of its species by altering the last vowel, Fonna, Fonna-e, Fonna-i, Fonna-o, Fonna-u; then others by Fonna-ha, Fonna-ka, and so on. This course would be liable to the same evils which have been noticed as belonging to the numerical method.

[40] Pref. clxxvi.

The names of plants (and the same is true of animals) have in common practice been binary only, consisting of a generic and a specific name. The Class and Order have not been admitted to form part of the appellation of the species. Indeed it is easy to see that a name which must be identical in so many instances as that of an Order would be, would be felt as superfluous and burdensome. Accordingly, Linnæus makes it a precept[41], that the name of the Class and the Order must not be expressed but understood: and hence, he says, Royen, who took Lilium for the name of a Class, rightly rejected it as a generic name, and substituted Lirium, with the Greek termination.

[41] Phil. Bot. s. 215.

Yet we must not too peremptorily assume such maxims as these to be universal for all classificatory sciences. It is very possible that it may be found advisable to use three terms, that of order, genus and [136] species, in designating minerals, as is done in Mohs’s nomenclature; for example, Rhombohedral Calc Haloide, Paratomous Hal Baryte.

It is possible also that it may be found useful in the same science to mark some of the steps of classification by the termination. Thus it has been proposed to confine the termination ite to the Order Silicides of Naumann, as Apophyllite, Stilbite, Leucite, &c., and to use names of different form in other orders, as Talc Spar for Brennerite, Pyramidal Titanium Oxide for Octahedrite. Some such method appears to be the most likely to give us a tolerable mineralogical nomenclature.

Sect. VII.—Diagnosis.

20. German Naturalists speak of a part of the general method which they call the Characteristik of Natural History, and which is distinguished from the Systematik of the science. The Systematick arranges the objects by means of all their resemblances, the Characteristick enables us to detect their place in the arrangement by means of a few of their characters. What these characters are to be, must be discovered by observation of the groups and divisions of the system when they are formed. To construct a collection of such characters as shall be clear and fixed, is a useful, and generally a difficult task; for there is usually no apparent connexion between the marks which are used in discriminating the groups, and the nature of the groups themselves. They are assumed only because the naturalist, extensively and exactly acquainted with the groups and the properties of the objects which compose them, sees, by a survey of the field, that these marks divide it properly.

The Characteristick has been termed by some English Botanists the Diagnosis of plants; a word which we may conveniently adopt. The Diagnosis of any genus or species is different according to the system we follow. Thus in the Linnæan System the Diagnosis of the Rose is in the first place given by its Class and Order: it is [137] Icosandrous, and Polygynous; and then the Generic Distinction is that the calyx is five-cleft, the tube urceolate, including many hairy achenia, the receptacle villous[42]. In the Natural System the Rose-Tribe are distinguished as being[43] ‘Polypetalous dicotyledons, with lateral styles, superior simple ovaria, regular perigynous stamens, exalbuminous definite seeds, and alternate stipulate leaves.’ And the true Roses are further distinguished by having ‘Nuts, numerous, hairy, terminated by the persistent lateral style and inclosed within the fleshy tube of the calyx,’ &c.