Vie CONG. INTERN. REPROD. ANIM. INSEM. ARTIF., PARIS, 1968, VOL. II the progestogens or progesterone in the mare in clinical practice as there is a possibility that this could lead to a cystic condition of the ovaries. This action of MGA in producing cystic ovarian disease in the mare could be of great value to someone contemplating collecting from a stallion at any given time. References Loy R. G. & Swan S.M. Effects of exogenous progestogens on reproductive phenomena in mares. J. Animal Sci. 25 821-826 Nalbandov A.V. Reproductive Physiology - P 156 2nd Edition 1964 W.H. Freeman & Co. Inc. San Francisco and London Pascoe R. Personal Communication Skinner and Bowen Puberty in the Welsh Mountain Stallion (1968) in Press. 1561