and the corresponding combinations with methylene blue, and amethyst violet may be mentioned.
The importance of these neutral staining solutions lies in the fact that they pick out definite substances, which would not be demonstrated by the individual components, and which we therefore call neutrophil.
Elements which have an affinity for basic dyes, such as nuclear substances, stain in these neutral mixtures purely in the colour of the basic dye; acidophil elements in that of one of the two acid dyes; whilst those portions of tissue which from their constitution have an equal affinity for acid and basic dyes, attract the neutral compound, as such, and therefore stain in the mixed colour.
The eosine-methylene blue mixtures are exceptional in so far, that it is possible with them, for a short time at least, to preserve active solutions, in which with an excess of basic methylene blue, enough eosin is dissolved for both to come into play. A drawback however of such mixtures is, that in them precipitates are very easily produced, which render the preparation quite useless. This danger is particularly great in freshly prepared solutions. In solutions, such as Chenzinsky's, which can be kept active for a longer time, it is less. Hence fresh solutions stain far more intensely and more variously than older ones, and are therefore used in special cases (see page 46). If the stain is successful the appearances are very instructive. Nuclei are blue, hæmoglobin red, neutrophil granulation violet, acidophil pure red, mast cell granulation deep blue, forming one of the most beautiful microscopic pictures.
For practical purposes, besides the iodine and iodine-eosine solution described below (see page 46) the following are especially used:
1. Hæmatoxylin solution with eosin or orange g.
| Eosin (cryst.) | 0.5 | |
| Hæmatoxylin | 2.0 | |
| Alcohol abs. | ||
| Aqu. dest. | ||
| Glycerine aa | 100.0 | |
| Glacial acetic acid | 10.0 | |
| Alum in excess |
The fluid must stand for some weeks. The preparations, fixed in absolute alcohol, or by short heating, stain in from half-an-hour to two hours. The hæmoglobin and eosinophil granules are red, the nuclei stain in the colour of hæmatoxylin. The solution must be very carefully washed off.