366 On the Doctrine of 



Having prefaced thus much, we may proceed to a con- 

 sideration of the value of the systematical opinions in ques- 

 tion. The three heads under which they can be most use- 

 fully examined are, 1. As to their practical accordance 

 with nature. 2. As to their accordance with each other. 

 3. As to the external evidence by which they are supported, 

 independently of the classification of tlieir authors. 



As to their practical accordance with nature, it is worthy 

 of remark, that the botanists who have adopted O ken's 

 ideas, have confined the application of them to the lowest 

 forms only of vegetation. Of these plants the structure 

 is so extremely simple, consisting only of cellules in 

 various states of juxtaposition, that it is not to be doubted 

 that they may be adapted to almost any system that can 

 be invented. The arrangement of their moleculse is be- 

 lieved by some to be influenced in a high degree by the 

 four elements ; hence it is possible that their tribes may 

 be particularly well fitted for falling into a quaternary 

 distribution. This opinion seems to be that which led 

 Nees to the application of a quaternary arrangement to 

 Fungi. But if it be admitted, that, for certain physi- 

 cal reasons, a division by four may possibly exist among 

 the simplest forms of vegetation, it does not necessarily 

 follow, that plants of a higher degree of evolution are 

 subject to the same law. Indeed Fries liimself seems to be 

 of this opinion, when he says, *' in superioribus sphgeris ob 

 organa plura major (numerus) admittendus quam in inferi- 

 oribus. Plant, homon. 21." He may therefore be sup- 

 posed to have adopted Oken's system only partially, and 

 in its general principles, and not with the intention of ap- 

 plying it to particulars. 



With respect to the system of the latter writer, as his 

 plan is applied to the whole kingdom of vegetation, and as 

 his ideas, with whatever peculiarity they may be expressed, 

 are not to be misunderstood, they present a fairer mark for 

 criticism. We have seen that, to obtain his four divisions, 

 he sets out with the assumption that the four degrees in 

 which four different parts of plants, viz. the root, stem, 

 leaves and flower, are respectively developed, necessarily 

 form the basis of any philosophical system ; for to be phi- 

 losophical it must depend upon the immutable workings of 

 nature as developed in generals, not in particulars, which 

 he finds to depend upon the four parts in question. Now 

 this doctrine arises out of certain abstract ideas of vege- 

 tation which prevail extensively among the philosophers of 



