THe experiments recorded here were initiated following upon the occurrence in this country of foot-and-mouth disease in a cow, which a short time previously had been injected for the purpose of inducing oestrus with a pituitary extract imported from the Continent. Mr D. A. E. Cabot, M.R.C.V.S., Chief Veterinary Officer of the Ministry of Agriculture, made reference to this interesting case in a discussion on foot-and-mouth disease at the First Imperial Veterinary Conference held in London (1938). Confirmation of the nature of the infection was obtained by the inoculation of test animals under experimental conditions with suitable material collected from the injected animal. Further investigations were made. Three ampoules containing pituitary extract were obtained from the distributors in London of the imported commercial preparation under discussion. These ampoules belonged to the same batch as the ampoule with the extract from which the cow had been inoculated. Messrs A. Eccles, M.R.C. V.S. and A. M. Graham, M.R.C.V.S., at the Experimental Station of the Foot-and-Mouth Disease Research Committee at Pirbright, tested this material for virus infectivity by the inoculation of cattle and guinea-pigs. They reported that all three samples of pituitary extract were contaminated with the virus of footand-mouth disease. In addition they produced evidence that the immunological type of the virus recovered from the extract in the ampoules was the same as that of the virus recovered from the cow, viz. Vallée and Carré 0. This and additional information left no doubt that the outbreak of the disease had been produced by the inoculation of the pituitary extract, and further that this extract had been prepared from the pituitary glands of cattle, which were very probably in the early stages of infection with foot-and-mouth disease at the time of slaughter.