PHILOSOPHICAL SOCIETY OF "WASHINGTON. 

 RECAPITULATION. 



119 



On this communication, Mr C. A. White remarked that he 

 hoped Mr. Ward would be able to furnish some further infor- 

 mation concerning the influence exerted upon a flora by the char- 

 acter of the country rocks. It is well known that the constitution 

 of the strata, influencing as it does the character of the soils which 

 cover them, had a further effect upon the native plants growing 

 above them. Thus the granite localities of the east were more fav- 

 orable to the growth of certain genera, for example, the Ericacese 

 than the magnesian limestones of the Mississippi valley. He hoped 

 that Mr. Ward might be able to ascertain how far these influences 

 affected other families of plants. 



Mr. Powell inquired what were the characters or character of 

 plants that had apparently disappeared from the local flora in the 

 comparison of the field results of the present time with those ob- 

 tained forty or fifty years ago. 



Mr. Ward replied that the missing species in the present lists 

 were not confined to any particular family, but were diffused con- 

 siderably among the several classes. 



The Society then adjourned. 



