The cells of Blepharisma which possess red pigment (blepharismin) show step‐up photophobic response (temporal ciliary reversal induced by a sudden increase in light intensity). Bleaching of the cells by cold shock raised a threshold light intensity for the response, Oxidation of red pigment that produced blue pigment did not raise the threshold for the response. The action spectrum for the step‐up photophobic response of the cells which possess normal red pigment had peaks at about 580, 540 and 490 nm, a value which coincided with peaks of an absorption spectrum of the red pigment. The absorption spectrum of oxidized pigment (blue pigment) shifted 20 nm toward infrared light. The action spectrum for the response of the cells which possess blue pigment also shifted 20 nm toward infrared light. Results suggest that red pigment might be involved in the step‐up photophobic response. Key words. Blepharismin, ciliary reversal, photoreceptors, photoresponse.

A newly devised, simple and highly reproducible method for fungal staining is reported. Grocott's method, in which methenamine-silver nitrate solution is employed, has been widely used for the staining of fungi in tissue sections, but it frequently produces heavy background staining because of sudden and progressive reaction in the methenamine-silver nitrate solution. We therefore replace the latter solution with an ammoniacal silver nitrate solution. This new method yields more consistent results in fungal staining without background staining, since the reaction time in the ammoniacal silver nitrate solution is prolonged. The present method is considered superior to Grocott's method with regard to its simplicity and reproducibility.