In his previous report (1) the author clarified that fluorescent NTS dye stains cancer cells more deeply at higher pH (pH 11.0) than normal cells and deduced the main reason for this to be due to the increased amount of nucleoprotein and a higher electrical potential of cancer cells. However, there emerges a question whether the amount of nucleoprotein of cancer cells is actually increased and this neads to be settled by quantitative estimation of basophilic protein per cell. Therefore, in order to ascertain this point, basophilic protein of Ehrlich ascites tumor cells, MH-134 ascites liver cancer cells. HeLa cells in culture, lymph nodes of gastric cancer bearing patients, and peripheral luecocytes of normal mice were stained with acid fast green FCF stain by Alfert's method, and the quantitative estimation of the protein per cell was conducted with microspectrophotometer. As the result it was confirmed that these cancer cells contain a larger quantity of the basic protein than lymph node. From these findings it has become clear that the fluorescent XTS. which is an acidic dye, stains cancer cells at a higher pH than normal cells because they contain a greater amount of basic protein than normal cells.