First leaves of 8-Day-Old, light grown corn seedlings were cut and then were floated in water or 1 X 10-s M N6 -benzyladenine (BA) solution at 28°C in the dark. Under these conditions, the leaf segments in water showed a significant lose chlorophyll, protein and RNA after 2 days. Treatment with BA delayed the appearance of these symptoms. Protease and RNase activities of segments floated in water were seen to increase. If leaf segments were preincubated with 35 methionine for five hours under light shortly after cut and then transfered to the treatments described above, the segments floated in BA solution had more radioactivity in the protein fraction than the segments floated in water. We concluded that BA can supress the increase of proteolytic activity normally associated with senescence. During senescence the respiration rate of leaf segments increased. Acid phosphatase activity increased strongly during the late stages of senescence of leaf segments. The contents of hemi· cellulose I, 11 and cellulose of the cell wall d.id not decrease significantly.