9 o 



ORGANIC EVOLUTION 



that there are important fundamental resemblances between 

 Solca and the members of the genus Viola. This funda- 

 mental resemblance in the midst of more superficial differ- 

 ences we indicate by classifying both Solca and Viola in 

 a common larger group which we call the family, in this 

 case the violet family or the Violacccc. As we have sev- 

 eral genera within the one family Violaccc?, so we have 



many different families of 



j 



plants, the daisy family 

 or Composite, the prim- 

 rose family or Primulacetz, 

 the rose family or Rosaccte, 

 and so on. Now all these 

 families mentioned have 

 certain o-eneral resem- 



O 



blances to one another, 

 such as the presence of 

 blossoms and seeds. Many 

 other kinds of plants are 

 without either blossoms or 



. 13. Soleaconcolor. -From An Illustrated i r i mosses 



Flora of the Xor/hern States and Canada, by the cour- SCCdS , IIS ail OSSeb, 



tesy of the authors and of Charles Scribner's Sons. ^ examplCe We distill- 



guish the former as flowering plants or phanerogams, and 

 the latter as flowerless plants or cryptogams. Thus we 

 have different grades in the classification to indicate dif- 



O 



ferent degrees of resemblance and divergence. 



Moreover, as we study the different groups of plants, we 

 find them very different in the complexity of their organ- 

 ization, in the extent to which their organs and tissues are 

 developed. Some, like the flowering plants, are highly 

 organized, showing very elaborate structure, while others 



