ON THE NATURE OF METACHROMASY

Abstract

Metachromasy is a phenomenon in cytological staining (1) . When a specimen is treated with some coloring matter solution, it is colored sometimes in the different color tone from the original solution. For instance, mucilage of various kinds of shellfish, basic substances of cartilage, granules of mast cells, metachromatin or volutin of protozoa, and some kinds of mucilages of plants-agar, alginic acid, gum arabic etc.-are colored deeply with special basic coloring matters like toluidine blue and thionine, while the color tone is reddish purple to red instead of blue.
The cause of metachromasy is considered, up to the present, to be as follows.
1) Adsorption of coloring matters to granules, or the occurance of coagulative precipitation (Möllendrof (2), Jancso (3) ) .
2) Change of the chemical structure of coloring matter induced by the combina-tion with a special ingredient of the cell material (Lison (4), Kelly and Miller (5), Holmes (6) ) .
3) The difference of stainability of the components of coloring matter mixture (such as acidic and alkaline structure, oxidative and reductive structure, and im-pure pure contamination) (Thorpe (7) ) .
4) The influence of rH, pH or special salts.
In the first case there should be the change of colloidal state of a coloring mat-ter in dispersion medium.
The second reason is most widely accepted. L. Lison comparatively recently investigated metachromasy at the point of this view. A substance which is stained metachromatically is called a chromotropica, for instance, the salts of high-molecular sulfuric acid ester like chondroitin sulfuric . acid, cholesterin sulfuric acid etc. In fact, some specimen such as mucilages of shellfish or basic substances of cartilage; proved with evident metachromasy, contain polysulfuric acid ester of high-molecular polysaccharide.
Lison tells that, when such special substances combine with the coloring matter, the structure of the coloring matter changes into the metachromatxc structure, andd only the coloring matter having at least one group of amino or imino radical as an auxochrome shows evident nrietachromasy.
Holmes noticed the tautomeric change of the structure. According to the recent investigation of Michaelis and Granich (8), the formation of polymer may cause metachromasy.
Before the discussion of the experimental results, we postulate the three questions:
1) Is it limited to the basic coloring matter containing at least one imino-group in the molecule which reveals metachromasy?
2) Is the chromotropic substance limited to only high-molecular sulfuric acid ester?
3) How is the physico-chemical mechanism of metachromasy ?