140 DESCRIPTIVE BOTANY. PARTI. 



this latter case, we are comparing an organ of second- 

 rate importance in the one series, with one of first-rate 

 in the other. 



If we could determine the natural affinities of all 

 plants, from a comparison of the characters deduced 

 from one series alone, and could likewise determine their 

 natural affinities from characters belonging to the other 

 series, it is evident that the two arrangements thus 

 established would strictly coincide. In the establishment 

 of the minor groups, botanists have recourse almost 

 exclusively to the reproductive organs ; as their cha- 

 racters are much better defined, and more varied than 

 those of the nutritive organs. The larger groups, how- 

 ever, are chiefly determined by characters belonging to 

 the nutritive and elementary organs, as we have shown 

 (art. 33.), where the exogenous structure tallies with 

 the dicotyledonous embryo, and the endogenous with the 

 monocotyledonous. 



(133.) Rules for firing Subordination of Character*. 

 The following rules may be advantageously con- 

 sulted, for determining a subordination of characters in 

 one or the other series. 



1. Where two organs, belonging to different classes 

 of functions, have the same relative value in their re- 

 spective series, that organ will possess the greatest value 

 which belongs to the most important function. 



2. Those organs of the same series, are of the 

 greatest value, which are of most general occurrence. 

 Thus the cellular tissue, which is universally present, is 

 the most important element in vegetation. 



3. The adhesion which frequently subsists between 

 an inferior and a superior organ, serves to point out the 

 relative value of any two of the former ; since it will 

 be the same as that which was previously established 

 for those of the latter, to which they respectively adhere. 



4. The greater degree to which an organ is liable 

 to vary, indicates an inferiority in its value. Thus 

 the shape of the leaves, is of little importance beyond 

 determining the specific distinctions of plants, and in 



