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Program Committee. — -Mrs. E. G. Britton, Jean Broadhurst, 

 C. Stuart Gager, F. J. Seaver. 



Local Flora Committee. — N. L. Britton, Chairman. 



Phanerogams. — E. P. Bicknell, N. L. Britton, C. C. Curtis, 

 K. K. Mackenzie, E, L. Morris, N. Taylor. 



Cryptogams. — Mrs. E. G. Britton, Philip Dowell, Tracy E. 

 Hazen, M. A. Howe, W. A. Murrill. 



The first number on the scientific program consisted of a 

 paper by Dr. H. A. Gleason. Dr. Gleason stated that the 

 present distribution of plants in the Middle West, from Ohio 

 to Iowa, can not be accounted for satisfactorily by any modern 

 environmental conditions. It is to be regarded as the culmina- 

 tion of a series of movements, begun at the close of the last glacial 

 period, and continued until the recent advent of civilization. 

 Three types of vegetation have taken part in these migrations: 

 the coniferous forest, the eastern deciduous forest, and the 

 western prairie. The movement of the coniferous forest has 

 been simply northward and it has now left the region almost 

 completely. Of the other two, four periods of migration may be 

 recognized: (i) A period of dry climate accompanied by the 

 extension of prairies far eastward. (2) A period with more 

 favorable climate accompanied by the restriction of the prairie 

 and the migration of the forest westward. During this period 

 forests occupied a large proportion of the land in Illinois and 

 Iowa, but probably did not extend so far west in Kansas and 

 Nebraska as at present. (3) A period of prairie fires, following 

 the advent of the Indians, during which the forest was driven 

 back to the position which it occupied a century ago. (4) The 

 last century, during which, with the cessation of prairie fires 

 the forests commenced an extraordinarily rapid advance upon 

 the prairie. 



The second announced paper was presented by Dr. C. C. 

 Trowbridge, of the department of physics of Columbia Univer- 

 sity. Dr. Trowbridge's paper on " Branch Movements of Certain 

 Trees in Freezing Temperatures" will be published in the Bulletin 

 of the Club. A brief summary of the results obtained in a series 

 of measurements made during last winter and the present one 

 is as follows : 



