CLASSIFICATION. 



469 



reasons, to extract the statement of 

 his doctrine in the very words he has 

 used. 



" Natural groups," according to this 

 theory,* are " given by Type, not by 

 Definition." And this consideration 

 accounts for that " indefiniteness and 

 indecision which we frequently find 

 in the descriptions of such groups, and 

 which must appear so strange and in- 

 consistent to any one who does not 

 suppose these descriptions to assume 

 any deeper ground of connection than 

 an arbitrary choice of the botanist. 

 Thus in the family of the rose-tree, 

 we are told that the ovules are rcry 

 rarely erect,thestlgmatausuallt/s\TX)Tp\e. 

 Of what use, it might be asked, can 

 such loose accounts be? To which 

 the answer is, that they are not in- 

 serted in order to distinguish the 

 species, but in order to describe the 

 famil}', and the total relations of the 

 ovules and the stigmata of the family 

 are better known by this general state- 

 ment. A similar observation may be 

 made with regard to the Anomalies 

 of each group, which occur so com- 

 monly, that Dr. Lindley, in his In- 

 troduction to the Natural System of 

 Botany, makes the 'Anomalies' an 

 article in each family. Thus, part of 

 the character of the Rosacese is, that 

 they have alternate stipulate leaves, 

 and that the albumen is obliterated; 

 but yet in Lowea, one of the genera 

 of this family, the stipulae are absent, 

 and the albumen isj^resent in another, 

 NeiUia. This implies, as we have 

 already seen, that the artificial char- 

 acter (or diagnosis, as Mr. Lindley 

 calls it) is imperfect. It is, though 

 very nearly, yet not exactly, connnen- 

 surate with the natural group ; and 

 hence in certain cases this character 

 is made to yield to the general weight 

 of natural affinities. 



"These view.s, — of classes deter- 

 mined by characters which cannot be 

 in words, — of propositions 



which state, not what happens in all 

 cases, but only u.sually, — of particu- 



* Hist. Sc. Id., ii. 120-122. 



lars which are included in a class, 

 though they transgress the definition 

 of it, may probably surprise the reader. 

 They are so contrary to many of the 

 received opinions respecting the use 

 of definitions and the nature of scien- 

 tific propositions, that they will pro- 

 bably appear to many persons highly 

 illogical and lui philosophical. But a 

 disposition to such a judgment arises 

 in a great measure from this, that 

 the mathematical and mathematico- 

 physical sciences have, in a great de- 

 gree, determined men's views of the 

 general nature and form of scientific 

 truth, while Natural History .has not 

 yet had time or opportunity to exert 

 its due influence upon the current 

 habits of philosophising. The appa- 

 rent indefiniteness and incon.sistency 

 of the classifications and definitions 

 of Natural History belongs, in a far 

 higher degree, to all other except 

 mathematical speculations ; and the 

 modes in which approximations to 

 exact distinctions and general truths 

 have been made in Natural History 

 may be wortiiy our attention, even 

 for the light they throw upon the best 

 modes of pursuing truth of all kinds. 



"Though in a Natural group of 

 objects a definition can no longer be 

 of any use as a regulative princij^le, 

 clas.ses are nottherefore left quite loose, 

 without any certain standard or guide. 

 The class is steadily fixed, though 

 not precisely limited ; it is given, 

 though not circumscribed ; it is de- 

 termined, not by a boundary line 

 without, but by a central point with- 

 in ; not by what it strictly excludes, 

 but by what it eminently includes ; 

 by an example, not by a precept ; in 

 short, instead of a Definition, we have 

 a Type for our director. 



"A Type is an example of any 

 class, for instance a species of a genus, 

 which is considered as eminently pos- 

 sessing the character of the class. All 

 the species which have a greater 

 affinity with this type-species than 

 with any others form the genus, and 

 are arranged about it, deviating from 

 it in various directions and difi"erent 



