262 



OHIO BrOLOGlCAL SURVEY 



Fig. 8. Blephavisl'ittis p 



HMiii (4i-o\viiiK in m Wrrily lidt tdinlaiid with :M)xc(1 Vegetation in 

 wliioli Agrimonia is Prominent. 



Even when tlieiiisclves undistnrbed, no other associations show so 

 quickly the effects of tlie changes in the land aronnd them as the 

 bottom-lands. The periodical freshets are very efficient carriers of seeds 

 from place to place. It is obvious that any change in the vegetation 

 at one place will change the character of the seeds carried down stream 

 into other unchanged societies. In tlie original condition of the coun- 

 try the seeds thus brought in by the freshets would represent largely 



