328 OPERATIONS SUBSIDIARY TO INDUCTION. 



of nature, in conformity to the foregoing principles, 

 has hitherto been found practicable only in one great 

 instance, that of animals. In the case even of vegetables, 

 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 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, 

 algse, and other substances whose organization 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 above this point., we do not find any recognisable 

 difference in the degree in which different plants 

 possess the properties of organization and life. The 

 dicotyledones and the monocotyledones are distinct 

 natural groups, but it cannot be said, even by a meta- 

 phor, that the former are more or less plants than the 

 latter. The palm-tree and the oak, the rose and the 

 tulip, are organized and vegetate in a different man- 

 ner, but certainly not in a different degree. The 

 natural classification of vegetables must therefore con- 

 tinue to be made without reference to any scale or 

 series; and the whole vegetable kingdom must form, 

 as it does in M. Comte's arrangement, one single step 

 or gradation, the lowest of all in the series of organized 

 beings, scientifically constructed for the purpose of 

 facilitating the investigation of the laws of organic 

 life. 



Although the scientific arrangements of organic 

 nature afford as yet the only complete example of the 

 true principles of rational classification, whether as to 



