THE variations in the chemical changes of the respirable substrate accompanying the process of fruit development and ripening of the different varieties of the tropical fruit Mangifera indica were investigated with the view of finding out the nature and the response of the substrate to the different methods of storage. Such investigations would provide helpful information for devising methods of storage of this delicate and easily perishable fruit. Accordingly, investigations as to the changes in the respirable substrate under the different conditions of storage were planned and carried out, first at a lower temperature of 8–12° C., secondly in ordinary room conditions of 28–32° C., and thirdly the effect was examined of different concentrations of ethylene gas as a means of artificial ripening.