218 Association of Geologists and JVaturalists. [Nov., 



from great depths in the soil, by the action of roots; after which 

 they are assimilated to the nature of the plant, and after fulfilling 

 their respective functions, are restored to the soil, where undergo- 

 ing a slow combustion they are refitted to pass into the organism 

 of the vegetable again; thus they go their rounds repeatedly, du- 

 ring the life of the tree. 



8. The frequent preservation of the bark in vegetables, in a 

 fossil state, is due to the large amount of inorganic matter it con- 

 tains. 



9. The amount of phosphates and alkalies in vegetables depends 

 in part on the season of the year when they are cut. 



10. A portion of the inorganic matter forms by a regular ar- 

 rangement the organized tissue of the vegetable, and is, probably, 

 an invariable quantity in every species, while in a healthy state. 



11. That advantage will probably arise from manuring trees 

 in raid-summer, that an abundance of food may be furnished to 

 the ripening fruit, and to be stored up in the tree for use the suc- 

 ceeding spring. 



Prof. H. D. Rogers exhibited a geological map of Pennsylvania. 

 He spoke of the numerous physical absurdities of the maps in 

 common use. He applies the names of nine periods of the day to 

 the divisions of the great geological day. 



He found independent and strong proofs of aqueous action on 

 the terraces, and of the aqueous theory of drift. 



Mr. Desor maintained the theory of soulevement against the 

 theory of waves, in the explanation of these plicae or flexures — 

 the plica? of the Jura chain are broken at the summit, and certain- 

 ly were not caused by a wave, but by uplifting of the Alps. 



Prof Agassiz remarked that the Appalachian chain resembles 

 the Jura; the first is ancient; the second, recent; showing that the 

 same causes, whatever they were, acted in the production of both. 

 The impulse which acted on the Jura was lateral, from the ele- 

 vation of the Alps; was it so in the Appalachian chain? There 

 were three separate elevations of the Jura, the last only of which 

 was caused by the Alps. 



Mr. S. S. flaldeman announced the discovery in the Trenton 

 limestone of a species of Aonia, a genus hitherto unknown to the 

 American continent. 



Prof Hall made a report on the Trilobites, Crinidea, &c., of 

 New York, in which he gave their distinguishing characters. The 

 Crinoids of the lower strata differ from those of the upper. He 

 thought the Atojps trilineatus and the Triarthus Beckii absolutely 

 identical. 



Prof H. D. Rogers offered some remarks on the geological age 

 of the rocks of Maine and New ]5runswick, which were supposed 

 to contain coal. From the examination of their fossils, he be- 



