CLASSii'lCATlOX BY SERIES. 



475 



ample, were ten thousand in the time of 

 Linnaeus, and are now probably sixty 

 thousand. It would be useless to en- 

 deavour to frame and employ separate 

 names for each of these species. The 

 division of the objects into a sub- 

 ordinated system of classification en- 

 ables us to introduce a Nomenclature 

 which does not require this enormous 

 number of names. Each of the genera 

 has its name, and the species are 

 marked by the addition of some epi- 

 thet to the name of the genus. In 

 this manner about seventeen hundred 

 generic names, with a moderate num- 

 ber of specific names, were found by 

 Linnaeus sufficient to designate with 

 precision all the species of vegetables 

 known at his time." And though the 

 luimber of generic names has since 

 greatly increased, it has not increased 

 in anything like the proportion of the 

 multiplication of known species. 



CHAPTER VIIL 



OF CLASSIFICATION BY SERIES. 



§ I. Thus far we liave considered 

 the principles of scientific classifica- 

 tion so far only as relates to the for- 

 mation of natural groups ; and at 

 this point most of those who have 

 attempted a theory of natural arrange- 

 n)ent, including among the rest Dr. 

 Whewell, have stopped. There re- 

 mains, however, another, and a not 

 less important portion of the theory, 

 which has not yet, as far as I am 

 aware, been systematically treated of 

 by any WTiter except M. Comte. This 

 is the arrangement of the natural 

 groups into a natural series.* 



The end of classification, as an in- 



* Dr. Whewell, in his reply (PhilosopJn/ 

 of Discovenj, p. 270) says that he "stopped 

 sliort of, or rather passed by, the doctrine 

 of a series of organised beings," because he 

 "thought it bad and nan-ow philosophy." 

 If he did, it was evidentl}' without under- 

 standing this form of the doctrine ; for he 

 proceeds to quote a passage from his "His- 

 tory," in which the doctrine he condemns 

 is designated as that of "a mere linear 

 progression in nature, which would place 



strument for the investigation of 

 nature, is (as before stated) to make 

 us think of those objects together 

 which have the greatest number of 

 important common properties, and 

 which, therefore, we have oftenest 

 occasion, in the course of our induc- 

 tions, for taking into joint considera- 

 tion. Our ideas of objects are thus 

 brought into the order most conducive 

 to the successful prosecution of induc- 

 tive inquiries generally. But when the 

 purpose is to facilitate some particular 

 inductive inquiry, more is required. 

 To be instrumental to that purj)ose, 

 the classification must bring those 

 objects together, the simultaneous 

 contemplation of which is likely to 

 throw most light upon the particular 

 subject. That subject being the Ia\\s 

 of some phenomenon or some set of 

 connected phenomena, the very phe- 

 nomenon or set of phenomena in ques- 

 tion must be chosen as the ground- 

 work of the classification. 



The requisites of a classification 

 intended to facilitate the study of a 

 particular phenomenon, are, first, to 

 bring into one class all Kinds of 

 things which exhibit that pheno- 

 menon, in whatever variety of forms 

 or degrees ; and, secondly, to arrange 

 those Kinds in a series according to 

 the degree in which they exhibit it, 

 beginning with those which exhibit 

 most of it, and terminating with 

 those which exhibit least. The prin- 

 cipal example, as yet, of such a classi- 

 fication is afforded by conjparative 

 anatomy and physiology, from which, 

 therefore, our illustrations shall be 

 taken. 



§ 2. The object being supposed to 

 be the investigation of the laws of 



each genus in contact only with the pre- 

 ceding and succeeding ones." Now the 

 series treated of in the text agrees with 

 this linear progression in nothing whatever 

 but in being a progt ession. 



It would svu-ely be possible to arrange 

 all places (for example) in the order of their 

 distance from the North Pole, though there 

 woulii lie not merely a plurality, but a 

 whole circle of places at every single grada- 

 tion in ttie scale. 



