Abstract
In vitro, phosphotungstic acid-hematoxylin undergoes a bathochromic change in its absorption spectrum comparable to the characteristic bathochromic metachromasia observed in stained tissues when it is reacted with appropriate excesses of organic basic groups such as amines, guanido and imidazole groups. The qualitative characteristic of the reaction is a shift from the PTA-H lake's usual absorption maximum of 560 mµ to 620 mµ. Quantitatively, a maximal reaction is obtained at an organic base: PTA-H ratio of 8:1; the quality of the base does not effect the reaction so that the eight bases could be all amines, four amines and four imidazoles, etc. Akylated amines and histone extracts form blue, bathochromic precipitates with PTA-H. These data delineate the anionic character of this lake and the nature of its metachromatic properties.