HYPOCOTYL GROWTH IN ETIOLATED CUCUMBER SEEDLINGS .2. CELLULAR ANALYSIS OF GROWTH

Cell division and elongation in hypocotyls of cucumber (Cucumis sativu s L.) were studied within 11 days after the beginning of seed imbibiti on. Cell division in the apical intercalary meristem occurred only for the first six days. Within this period, the number of cells in the hy pocotyl increased sixfold. After germination, the size of the intercal ary meristem and the number of cells therein rose for only 2 days and then fell. By the sixth day, meristematic activity ceased, and subsequ ent growth proceeded only by cell elongation. Comparative analysis of cell growth in the hypocotyl and root showed that, in the root, relati ve rates of cell proliferation and elongation were higher, whereas the duration of mitotic cycles and elongation were shorter than in the hy pocotyl.