e. Spirilla and Spirochætes.
1. Spirillum of Recurrent Fever. Stain in sections with Levaditi’s silver-method, or with Nikiforoff’s method:—
1. Fix for 24 hours in equal parts of a 5 per cent water solution of potassium bichromate and a saturated solution of mercuric chloride in 0.6 per cent sodium chloride.
2. After-harden in graded alcohols in the incubator.
3. Imbed in paraffin.
4. Stain 24 hours in a mixture of alcoholic 1 per cent solution of tropæolin 5 cc., concentrated watery methylene-blue solution 10 cc., caustic potash solution (1:1000) 2 drops.
5. Wash in water.
6. Dip several times in a mixture of equal parts of absolute alcohol and ether.
7. Oil of bergamot; xylol; balsam.
The spirillum of African relapsing fever stains with the same stains as the spirillum Obermeieri. The spirochætes of Vincent’s angina and fowl-spirillosis, and the spirochæte refringens stain with watery aniline dyes and with Giemsa’s stain; in section they are stained by the Levaditi method.