Earlier, when studying the responses of plants to treatment with certain types of chemicals, we found that melaphene, the melamine salt of bis(methylol)phosphinic acid, at ultralow concentrations exhibits regulatory activity [1]. Studies of the effect of melaphene on the regulation of growth and development of the unicellular alga Chlorella , as well as on the rate of photosynthesis, respiration, and metabolic heat emission as an index of energy status of cells, showed that melaphene had the greatest effect at concentrations of 3 × 10 -9 -3 × 10 -10 å [1]. These results and published data allowed us to conclude that the effect of melaphene on energy processes and metabolism in plants is similar to the effect of phytohormones of the cytokinin series [2].In view of these facts, it was logical to perform a comparative study of efficiency of melaphene and kinetin, taken at equimolar concentrations, on the growth and energy processes in the unicellular alga Chlorella vulgaris. This was the goal of this work.It is known that exogenous kinetin contained in culture medium stimulates the growth of plants, affecting cell division by shortening cell cycles [3,4]. Figure 1 illustrates the effect of melaphene and kinetin on the growth rate of alga suspension. It can be seen that the growth rate of cells in the presence of 3 × 10 -10 M melaphene was comparable to that recorded in the presence of 3.5 × 10 -10 M kinetin. This fact provides evidence that, similarly to kinetin, melaphene accelerates cell division.Kinetin and melaphene had similar effects on the intensity of energy processes as well. The rates of energy processes were monitored polarographically by the rate of oxygen emission/consumption [5]. The results of comparative study of the effects of kinetin and melaphene on the rate of oxygen consumption by plant cells are shown in Fig. 2. As seen from this figure, 3 × 10 -10 M melaphene had a strong stimulatory effect on respiration rate. The degree of stimulation of oxygen consumption in the presence of melaphene was comparable to that observed in the presence of 3.5 × 10 -10 M kinetin. Possibly, melaphene, similarly to cytokinin [2, 6], affects the rate of electron transport and stimulates the activity of some enzymes of the electron-transport chain.Interesting results were obtained when studying the effect of melaphene on the rate of photosynthesis in Chlorella in comparison to kinetin. Figure 2 shows that the responses of Chlorella cells to treatment with kinetin and melaphene were similar. Note that not only the direction of effect (i.e., stimulation of the rate of oxy-