478 



OPERATIONS SUBSIDIARY TO INDUCTION. 



from Insects, Insects from Mollusca, 

 &c. When so formed, the primary 

 natural groups will compose the series 

 by mere juxtaposition without redis- 

 tribution, each of them corresponding 

 to a definite portion of the scale. In 

 like manner each family should, if 

 possible, be so subdivided that one 

 portion of it shall stand higher and 

 the other lower, though >oi course con- 

 tiguous, in the general scale ; and only 

 when this is impossible is it allowable 

 to ground the remaining subdivisions 

 <m characters having no determinable 

 connection with the main phenomenon. 

 Whei'e the principal phenomenon 

 so far transcends in importance all 

 other properties on which a classifica- 

 tion could be grounded, as it does in 

 the case of animated existence, any 

 considerable deviation from the rule 

 last laid down is in general sufficiently 

 guarded against by the first princi- 

 ple of a natural arrangement, that of 

 forming the groups according to the 

 most important characters. All at- 

 tempts at a scientific classification of 

 animals, since first their anatomy and 

 physiology were successfully studied, 

 have been framed with a certain de- 

 gree of instinctive reference to a na- 

 tural series, and have accorded in 

 many more points than they have 

 differed, with the classification which 

 would most naturally have been 

 grounded on such a series. But the 

 accordance has not always been com- 

 plete ; and it still is often a matter 

 of discussion, which of several classi- 

 fications best accords with the true 

 scale of intensity of the main pheno- 

 menon. Cuvier, for example, has 

 been justly criticised for having 

 formed his natural groups with an 

 undue degree of reference to the 

 mode of alimentation, a circumstance 

 directly connected only with organic 

 life, and not leading to the arrange- 

 ment most appropriate for the pur- 

 poses of an investigation of the laws 

 of animal life, since both carnivorous 

 and herbivorous orfrugivorous animals 

 are found at almost every degree in 

 the scale of animal perfection. Blain- 



I 



ville's classification has been corv 

 sidered by high authorities to be free 

 from this defect, as representing cor- 

 rectly, by the mere order of the prin- 

 cipal groups, the successive degeneracy 

 of animal nature from its highest to 

 its most imperfect exemplification. 



§ 5. A classification of any large 

 portion of the field of nature in con- 

 formity to the foregoing principles 

 has hitherto been found practicable 

 only in one great instance, that of 

 animals. In the case even of vege- 

 tables, the natural arrangement has 

 not been carried beyond the formation 

 of natural groups. Naturalists have 

 found, and probably will continue to 

 find, it impossible to form those groups 

 into any series, the terms of which 

 correspond to real gradations in the 

 phenomenon of vegetative or organic 

 life. Such a difference of degree may 

 be traced between the class of Vas- 

 cular Plants and that of Cellular, 

 which includes lichens, algae, and 

 other substances whose organisation 

 is simpler and more rudimentary than 

 that of the higher order of vegetables, 

 and which therefore approach nearer 

 to mere inorganic nature. But when 

 we rise much abovo this point, we do 

 not find any sufficient difference in the 

 degree in which different plants pos- 

 sess the properties of organisation and 

 life. The dicotyledons are of more 

 complex structure, and somewhat more 

 perfect organisation, than the mono- 

 cotyledons 5 and some dicotyledonous 

 families, such as the Compositae, are 

 rather more complex in their organisa- 

 tion than the rest. But the differences 

 are not of a marked character, and do 

 not promise to throw any particular 

 light upon the conditions and laws of 

 vegetable life and development. If 

 they did, the classification of vege- 

 tables would have to be made, like 

 that of animals, with reference to the 

 scale or series indicated. 



Although the scientific arrange- 

 ments of organic nature afford as yet 

 the only complete example of the true 

 principles of rational classification, 



