290 OPERATIONS SUBSIDIARY TO INDUCTION. 



been found practicable only in one great instance, that of 

 animals. In the case even of vegetables, the natural arrange- 

 ment 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 pheno- 

 menon of vegetative or organic life. Such a difference of 

 degree may be traced between the class of Vascular Plants 

 and that of Cellular, which includes lichens, alga3, and other 

 substances whose organization is simpler and more rudimen- 

 tary than that of the higher order of vegetables, and which 

 therefore approach nearer to mere inorganic nature. But when 

 we rise much above this point, we do not find any sufficient 

 difference in the degree in which different plants possess the 

 properties of organization and life. The dicotyledons are of 

 more complex structure, and somewhat more perfect organiza- 

 tion, than the monocotyledons : and some dicotyledonous 

 families, such as the Compositse, are rather more complex in 

 their organization than the rest. But the differences are not 

 of a marked character, and do not promise to throw any par- 

 ticular light upon the conditions and laws of vegetable life and 

 development. If they did, the classification of vegetables 

 would have to be made, like that of animals, with reference to 

 the scale or series indicated. 



Although the scientific arrangements of organic nature 

 afford as yet the only complete example of the true principles 

 of rational classification, whether as to the formation of groups 

 or of series, those principles are applicable to all cases in which 

 mankind are called upon to bring the various parts of any 

 extensive subject into mental co-ordination. They are as much 

 to the point when objects are to be classed for purposes of art 

 or business, as for those of science. The proper arrangement, 

 for example, of a code of laws, depends on the same scientific 

 conditions as the classifications in natural history ; nor could 

 there be a better preparatory discipline for that important 

 function, than the study of the principles of a natural arrange- 

 ment, not only in the abstract, but in their actual application 

 to the class of phenomena for which they were first elaborated, 



