70 FIELD AND FOREST. 



Prof. Seaman stated that in the medical lecture room of Howard 

 University, it was so marked that the class then undergoing examina- 

 tion, ran out of the building, saying that they could see the vibration 

 of the blackboard against the walls. This was at 11.40 o'clock, and 

 the shock lasted perhaps 10 seconds. Other members heard the rat- 

 tling of windows, dishes, &c., indoors, but others, were out of doors 

 at the time, noticed nothing. 



Allusion was also made to a shock felt here very distinctly in 1852. 



J. J. Chickering presented a collection of a dozen or more nests- 

 and eggs of birds of the district. 



Mr. Ward mentioned the finding of two localities of Phoradend?-on 

 jiavescem, (Mistletoe,) on Rock Creek, and stated that in both in- 

 stances it was found upon old decaying trees of nyssa miiltiflora 

 (Sweet Gum.) Prof. Chickering spoke of several localities south of 

 Alexandria. 



Jan. 24th, 1876, (iggth meeting.) 



Lieut. W. L. Carpenter was elected a member. 



Prof. Chickering then read a paper upon the distribution of certain 

 species of Aster. 



Mr. Ward read a paper "On the eccentricity of the pith of Rhus 

 Toxicodendron,'''' from which we make the following extract : 



The whole subject may therefore be thus briefly summed up : 



1 . The pith of the Poison Ivy, wherever it is of moderate size and 

 is found adhering closely, either to the bark of a living tree or to soft 

 decayed wood at the surface of its support, is located from three to ten 

 times nearer the inner side of the stem, and often still more eccentric- 

 ity. 



2. This eccentricity diminishes and frequently disappears altogeth- 

 er at points where there is no attachment by the rootlet. 



3. It is greatly reduced in vines which cling to anything which the 

 rootlets are unable to penetrate, as a stone wall or a post which is not 

 decayed. 



4. It diminishes relatively as the stem increases in size. 



Prof. Doolittle read a paper, also, upon Phorade7idron flavescens, 

 or American Mistletoe. 



