As reported in the previous paper in the belief that tha acceleration of the cell-membrane permeability and the resultant inflow of external-fluid into the cell are responsible for the dispersion of vital-staining dye particles within the cell when the antigen is made to act on peritoneal monocytes from the rabbits sensitized with bovine serum, the author estimated the fluctuation in the permeability of Janus green and Nile blue both before and after the action of antigen. In this series of experiments the author employed the conventional supra-vital staining combined with the method for the fixation of the dye by potassium mercuric iodide solution devised by Seno, Haba, Maki et al. and estimated the changes in the permeability under a microspectrophotometer. As the result, it has been verified that cells coming in contact with antigen increase in the cell-diameter by about 2.5μ and the permeability for dyes is accelerated 1.71 to 2.22 times in one minute.