THE DEHISCENCE OF ANTHERS BY APICAL PORES. 209 



The nature of this correlation we cannot consider here* 

 For the present, we are concerned only with ascertaining 

 if an interdependence really exists. An examination of 

 the apically dehiscent genera and species alone yields very 

 convincing evidence in favor of this hypothesis, but theories 

 based upon one class of data are open to criticism and 

 especially so when the mass of material is so small as it 

 necessarily is in the few apically dehiscent genera assigned 

 to the Dilleniaceous or the Solanum-Cassia type. 



ABERRANT NATURE OF APICALLY DEHISCENT FORMS IN 



THEIR SYSTEMATIC GROUPS. 



A satisfactory kind of supplementary evidence will be 

 furnished by a comparison of the apically dehiscent genera 

 from the several families with the other members of the 

 same systematic group. If in addition to an approximate 

 conformity to the characteristics of their own type in an 

 artificial class limited primarily by a single character, the 

 several genera are found to be aberrant in the groups of 

 the phylogenetic system in respect to the assemblage of 

 their floral characteristics, we shall be justified in conclud- 

 ing that there is some direct and demonstrable relation 

 between the selected character and the others pertaining 

 to the flowers under consideration. 



A thorough comparison such as that here suggested in- 

 volves numerous almost insurmountable difficulties. Tax- 

 onomists are by no means agreed as to the limitations of 

 sj r stematic groups or as to their monophyletic or poly- 

 phyletic origin, and under these circumstances what shall 

 serve as our basis of comparison? Not only are the limits 

 of groups variously and of ttimes ill defined but the data 

 available on the floral structure of species or genera are 



sometimes very meager. The labor involved in searching 

 through many volumes of descriptions and figures to secure 

 the data for such comparisons is very great and even then 



