Concanavalin-A (Con-A) competes with insulin for the insulin binding sites of the receptor, an event resulting in overlapping bonds. If the saccharide components of the receptor are subjected to periodate treatment the binding of insulin decreases and so does the imprinting evoked by it. Simultaneously, the binding of Con-A increase immediately after the treatment and 24 hours following the insulin imprinting. This phenomenon indicates that though the two ligands (i.e. insulin and Con-A) overlap on the intact receptor, alterations in the saccharide component influence their binding though not in the same manner and not in the same direction. Periodate treatment, similarly as observed in mammalian lymphocyte cultures, enhanced the division of Tetrahymenas and the peak of Con-A binding occurred parallel to the peak of division after periodate treatment of equal duration. Periodate treatment disturbed not only the binding of Con-A but that of other lectins as well. It has been concluded that hormonal imprinting requires a physiological condition of the membrane and any disturbance of the membrane will lead to a decrease in the efficacy of imprinting.