The nature and rate of regeneration of a 23- yr.-old bluestem pasture under complete protection from grazing were studied near Lincoln, Nebraska. The pasture adjoined a large tract of True Prairie, 0.5 mi. long and 0.25 mi. wide, of which it was originally a part. The prairie, of the upland mid- grass type, had not been grazed for at least 40 yr., and probably only moderately since the disappearance of the bison. It is used for the production of hay and is mowed annually in late summer or autumn. A portion of the pasture adjoining the prairie was separately fenced and thus closed to livestock in the spring of 1937. This part was 31 rods long and 4.5 rods wide. It extended northward from the top of a low hill down a gentle slope and included...