SUMMARY Oral or intraperitoneal administration of cortisone acetate to suckling hedgehogs had very little effect on the ability of the gut to absorb antibody. Such treatment had little effect upon the amount of alkaline phosphatase in the duodenum. These results contrast markedly with those described in the rat and mouse. The amount of alkaline phosphatase in the hedgehog duodenum declines during the first 30 days of the suckling period. A transient increase occurs towards the end of this time, followed by a decline to adult levels. The gut of the young hedgehog retains its capacity to absorb antibody for an unusually long period—certainly up to 41 days of age. Young hedgehogs begin to take solid food at 25 days and continue to suckle for at least a further 15 days. The transitional period during which the diet is altering from one of milk only to that of the adult is very much longer in this species than in the rat and mouse.