The meristematic cell flow or percentage of cells formed per unit of time is constant under standard experimental conditions. In this paper, the cell flow is measured directly under the action of the colchicine, by observing the cell increase at metaphase, and with the caffeine by observing the production and increase of binucleate cells in successive units of time. The analysis of different concentrations and periods of treatment has shown the 2hr treatment of 0.05% colchicine and the 4hr treatment of 0.1% caffeine as the more effective in order to measure the cellular increase. Both drugs have a depressive effect upon the division cycle as a whole, in a uniform and homogeneous fashion. Colchicine slows down the division cycle in a 50% and caffeine in a 60% of the normal cell flow. This depressing effect must be borne in mind in any estimate of the cycle time and mitotic rate by means of these drugs.