The effect of salts on the pars distalis of R. cyanophlyctis was studied by placing them in sodium chloride, potassium chloride (0.5%), distilled water and tapwater (control) for 15 days. In frogs kept in NaCl solution basophil type 3 cells (B3) showed marked hypertrophy and degranulation, whereas the B3 cells of frogs kept in KCl solution showed the hypertrophy and accumulation of secretory granules inside their cytoplasm. The B3 cells of frogs kept in distilled water or tapwater showed no changes. The other cell types of the pars distalis (A1 and A2 acidophils; B1 and B2 basophils) remained unaffected. It is concluded that the B3 cells are the probable source of adrenocorticotrophin and that the adenohypophyseal hormone(s) play a role in the maintenance of water and salt balance in R. cyanophlyctis.