BOTANICAL ANALYSIS 221 



older in time, and tlierei'ore more constant and less inclined to vary, 

 while those characterizinjj the lesser groups are more recent in their 

 origin, and nnicli inclined to vary in diflerent individuals. They are, 

 therefore, less trustworthy and have to be considered in connection 

 with others. It is for this reason that the most frequented ifl'erences of 

 opinion concerning classification among botanists relate to genera, 

 species and varieties. 



