BOTANY OF LA SALINE COUNTY. 



33 



just alike it may be slightly downy or a little hairy 

 instead of smooth, &c. Sometimes these variations 

 are so great as to almost constitute distinct species and 

 yet the extreme forms are so connected by intermediate 

 forms that we cannot regard them as more than widely 

 divergent varieties. In such cases we suspect that the 

 classification is at fault, that the genus is really a 

 species of some other genus and that its species are 

 really only varieties and that these have crossed again 

 and again, producing an endless variety of variant 

 forms. 



However there is always a trace of a tendency to 

 vary even among the most staid and unvarying of 

 species. We give below the length and breadth of 

 some leaves of the elm, smilacina, willow and cornus, 

 in each case all from the same plant, and all full 

 grown. 



The above are not extreme cases but such as may be 



