1. Solutions containing NH4OH and NaOH, and CO2 and HCl may be used to produce various combinations of extracellular and intracellular reactions in starfish eggs, Gonionemus, and Nitella cells. 2. Staining by basic dyes is, with a constant intracellular reaction, favored by increased extracellular alkalinity. With a constant extracellular reaction, staining is hindered by increased intracellular alkalinity. 3. These facts are in opposition to the view that staining of cells by basic dyes is chiefly governed by a combination of the dyes with cell proteins. It is more in harmony with the view that the combination is with a substance or substances of acid nature.