Sprouts of potato tubers allowed to develop in a dark, dry environment at 60 F developed tip necrosis which was alleviated by application of calcium salts. Successive removal of sprout tips at an eye led to the formation of sprout clusters of sufficient density to cause penetration of the tuber by new sprouts arising from the cluster. The length at which the sprouts were pruned determined the density of the cluster and consequently the likelihood of internal sprouting. It is theorized that the localized calcium deficiency in severe cases could lead to the formation of similar rosettes and therefore, is implicated as a possible cause of internal sprouting.