of meetings the next meeting would come on Decoration Day, 

 May 30. According to the new schedule the next meeting 

 should be held on the third Wednesday, i.e.. May 16. Since it 

 would be impossible to arrange a program for this meeting with 

 due announcement in the Bulletin of the New York Academy 

 of Sciences, he moved that this second meeting in May be 

 omitted. This was so voted by the Club. 



The scientific part of the program consisted of an illustrated 

 lecture by Dr. Raymond H. Wallace of Columbia University, 

 entitled, "The Development of Plant Tumors in Response to 

 Ethylene Gas." A summary of this lecture follows: 



A detailed histological and cytological study shows that the 

 intumescences which develop in the buds and stems of Trans- 

 parent apple in response to stimulation by ethylene gas arise 

 through three fundamental changes in the tissues, namely: 

 solution of walls, hypertrophy of cells, and proliferation of cells. 



The walls are corroded away very irregularly by solution 

 processes induced or accelerated by ethylene gas. Certain 

 restricted portions of the secondary walls may be entirely cor- 

 roded away before adjacent areas are appreciably modified. 

 The middle lamella goes into solution just prior to or at the 

 time of the complete solution of the secondary thickenings. 

 The solution of the walls results ultimately in the more or less 

 complete separation of the cells from tissue continuity and the 

 rounding up of the individual protoplasts. 



All living elements between the phellogen and the true 

 cambium may undergo this corrosion of walls and the libera- 

 tion of the cells from the tissue masses. Even the non-living 

 elements such as the bast fibres and walls of the young xylem 

 vessels are often digested away. 



Very distinct corrosion zones, which apparently represent 

 diffusion tracts for the ethylene or the ethylene stimulus, are 

 usually present in young intumescences. 



Great hypertrophy of cells usually accompanies the solution 

 of the walls, but this enlargement of the cells is not necessarily 

 the primary cause for the freeing of the cells from tissue con- 

 tinuity. The free cells in the outgrowths may vary from normal 

 ones only 25 by 30 microns to giant ones as much as 50 by 360 

 microns. 



The phellogen frequently exhibits a more striking hyper- 

 trophy than any other tissue of the stem. 



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