The processes which take place in peaches stored under conditions that favour development of woolly breakdown, were found to be connected with the metabolism of the pectic substances. In fruit held under conditions that ensure its normal ripening (above 8°), a gradual degradation of protopectin to soluble pectin occurs and the amount of pectates remains constant. However, in fruit that is held under conditions which favor woolly breakdown (below 8°), the insoluble pectic fractions begin to increase after approximately 2 weeks' storage. As a result, the total amount of pectic substances appears to increase. This change evidently occurs partially due to the action of pectin-methyl-esterase. During normal ripening the activity of this enzyme increases until the fruit attains full ripeness and then begins to decrease. In fruit with incipient woolliness, enzyme activity is initially low, and only begins to rise during the second stage of storage. Thus, an insoluble low-methoxyl pectin of high molecular weight is formed in the cell walls, which is capable of 'holding' water in a gel-like structure. It is suggested that this could be the reason for loss of juiciness in woolly peaches.