a method for the detection of antitoxoplasma antibody in serum, based on the finding that Toxoplasma gondii cells (from peritoneal exudate in mice) are fairly well stained with alkaline methylene blue, whereas organisms in a serum that contains specific antibody have no affinity for the dye; furthermore, normal toxoplasma cells become rounded, and the nucleus and cytoplasm deeply stained, when treated with methylene blue; conversely, when dye is mixed with organisms and antibody, the cells retain their crescent shape and only the shrunken nuclear endosome is stained.