In 1952 control groups of finewooled 6-yr-old Soviet Merino and 5-yr-old Precoce ewes at the Stavropol Sheep and Goat Breeding Institute, and semi-finewooled 4- to 5-yr-old Dagestan Mountain ewes at the Institute of Animal Breeding of the Dagestan Academy of Sciences, were fed the normal ration without concentrates, and similar experimental groups were fed supplementary concentrates. Ewes of each breed were inseminated with semen from 1 ram of their own breed. Skin samples were taken from the sides of the lambs 1-2 days after birth. Fibre length and density were significantly greater in samples from the experimental lambs than in those from the controls; the difference was greatest for the Soviet Merino and least for the Dagestan Mountain. Fibre density was almost 43% less in the Dagestan Mountain than in the finewooled samples, and 10% less in Precoce than in the Soviet Merino fibres. Samples from the finewooled lambs averaged 29% formed fibres and 71% follicles v. 44. 7 and 55. 3% resp. for the Dagestan Mountain. G. R.