Staining Methods.
Fresh blood may be stained by mixing with Ferrier’s fuchsine solution:—
| Fuchsine | 1 | grm. |
| Distilled water | 150 | c.c. |
Dissolve and add
| Alcohol (80 per cent.) | 50 | c.c. |
| Neutral glycerine | 200 | c.c. |
A spot of this solution is mixed with the blood on a slide by means of a mounted needle, and covered with a clean cover-glass. The red corpuscles are slightly stained, while the nuclei of the white corpuscles are stained a bright crimson, and the “blood plates” a deep pink colour.
Stained preparations may also be obtained by using Toison’s fluid, which serves also for diluting the blood in order to determine the exact number of red and white corpuscles present by means of Gowers’ or the Thoma-Zeiss hæmocytometer. It is prepared thus:—
| Glycerine | 30 | c.c. | 1 | oz. |
| Sodium sulphate | 8 | grms. | 2 | drms. |
| Sodium chloride | 1 | grm. | 15 | grs. |
| Methyl violet | ·25 | grm. | 4 | grs. |
| Distilled water | 160 | c.c. | 5 | oz. |
It stains the nuclei and blood plates, but does not alter the shape of the red cells. It requires to be made up fresh occasionally as torulæ are apt to form and multiply in it.
Dried films may be stained with hæmatoxyline, picrocarmine, or any of the general stains. The nuclei of the leucocytes may be stained rapidly in a couple of minutes in a one per cent. solution of methyl violet, washing in water, drying between blotting paper and mounting in balsam. The best method for general purposes is to stain with a saturated aqueous solution of methyl blue for half an hour or longer. Wash in water, and then stain for ten minutes in a half saturated aqueous solution of eosine. In this way the eosinophile granules of the leucocytes and the red corpuscles, are stained by the eosine, while the nuclei of the leucocytes are stained by the methyl blue.
Kanthack and Drysdale recommend that the film should first be stained with a half per cent. solution of eosine in 50 per cent. alcohol, then washed, dried and fixed in the flame, and stained for a short time in Löffler’s solution of methylene blue (p. [104]).
These films may be stained for micro-organisms in the way described for cover-glass preparations (p. [112]).