MATERIALS AND METHODS

reported that certain pyrimidine sulfa compounds could induce testicular hyper-plasia and enlarged combs in cockerels. Turner and Kumaran (1949) explained thèse facts by assuming an increased gonadotrophin sécrétion by the anterior pituitary gland. An alternative explana-tion for the observed phenomena is in-creased sensitivity of the gonads to endogenous gonadotrophins. Experiments reported in the présent paper were designed to elucidate the mode of action of sulfamethazine, one of the sulfa pyrimidine compounds found by Turner and Kumaran (1949) to be effec-tive in inducing preçocious sexual matur-ity. During our experiments a marked effect was observed on the thyroid size and activity