506 OPERATIONS SUBSIDIARY TO INDUCTION. 



properties, can answer this purpose. To distinguish the common daisy 

 from all other species of plants would require the specification of many 

 characters. And a name can not, without being too cumbrous for use, give 

 indication, by its etymology or mode of construction, of more than a very 

 small number of these. The possibility, therefoi'e, of an ideally perfect 

 Nomenclature, is probably confined to the one case in which we are hap- 

 pily in possession of something approaching to it — the Nomenclature of 

 elementary Chemistry. The substances, whether simple or compound, with 

 which chemistry is conversant, are Kinds, and, as such, the properties which 

 distinguish each of them from the rest are innumerable ; but in the case of 

 compound substances (the simple ones are not numerous enough to require 

 a systematic nomenclature), there is one property, the chemical composi- 

 tion, which is of itself sufficient to distinguish the Kind ; and is (with cer- 

 tain reservations not yet thoroughly understood) a sure mark of all the 

 other properties of the compound. All that was needful, therefore, was to 

 make the name of every compound express, on the first hearing, its chem- 

 ical composition ; that is, to form the name of the compound, in some uni- 

 form manner, from the names of the simple substances which enter into it 

 as elements. This was done, most skillfully and successfully, by the French 

 chemists, though their nomenclature has become inadequate to the conven- 

 ient expression of the very complicated compounds now known to chemists. 

 The only thing left unexpressed by them was the exact proportion in which 

 the elements were combined ; and even this, since the establishment of the 

 atomic theory, it has been found possible to express by a simple adaptation 

 of their phraseology. 



But where the characters which must be taken into consideration, in 

 order sufficiently to designate the Kind, are too numerous to be all signified 

 in the derivation of the name, and where no one of them is of such })repon- 

 derant importance as to justify its being singled out to be so indicated, we 

 may avail ourselves of a subsidiary resource. Though we can not indicate 

 the distinctive properties of the Kind, we may indicate its nearest natural 

 affinities, by incorporating into its name the name of the proximate natural 

 group of which it is one of the species. On this principle is founded the 

 admirable binary nomenclature of botany and zoology. In this nomen- 

 clature the name of evei'y species consists of the name of the genus, or 

 natural group next above it, with a word added to distinguish the particu- 

 lar species. The last portion of the compound name is sometimes taken 

 from some one of the peculiarities in which that species differs from others 

 of the genus ; as Clematis mtegrifolia, Potentilla alba, Viola palustris, 

 Artemisia vulgaris; sometimes from a circumstance of an historical na- 

 ture, as Narcissus jt?oei«ci<s, Potentilla tormentilla (indicating that the plant 

 is that which was formerly known by the latter name), Exacum Candollii 

 (from the fact that De Candolle was its first discoverer) ; and sometimes 

 the word is purely conventional, as Thlaspi hursapastoris, Raimnculus 

 thora; it is of little consequence which ; since the second, or, as it is usually 

 called, the specific name, could at most express, independently of conven- 

 tion, no more than a very small portion of the connotation of the term. 

 But by adding to this the name of the superior genus, we may make the 

 best amends we can for the impossibility of so contriving the name as to 

 express all the distinctive characters of the Kind. We make it, at all 

 events, express as many of those characters as are common to the proxi- 

 mate natural group in M-hich the Kind is included. If even those common 

 characters are so numerous or so little familiar as to require a further ex-. 



