ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 525 



(4) Staining' and Injecting-. 



New Staining Method for Demonstrating the Finer Structure of 

 Bacteria.* — Herr K. Nakanishi describes a method in which the stain is 

 first deposited on a slide. The most suitable pigment was found to be 

 methylen-blue B.B. It is easily soluble in water, blood-serum, and 

 other animal fluids. Some of the saturated aqueous solution is filtered 

 • on to a slide, and smeared up and down with filter-paper. The stain is 

 wiped off so as to leave only a thin layer of a sky-blue colour. Or a 

 layer of pigment may be deposited on the slide by boiling until it dries, 

 and the excess afterwards rubbed away until the desired colour is obtained. 

 A small drop of the fluid to be examined is placed on a cover-glass, and 

 this on the stained slide. 



This method is very suitable for blood and for blood-parasites, as 

 well as for bacteria. In bacteria it demonstrates the presence of a 

 nucleus which is stained red, the rest of the protoplasm being blue. 

 Flagella and spores do not stain. By this method the various stages of 

 cell-division are easily followed. 



Staining Bacteria in Sections simultaneously treated by Van 

 Gieson's Method.| — Herr G. Dreyer states that the following procedure 

 gives excellent results and beautiful pictures. The tissue is fixed with 

 formalin and imbedded in paraffin. The sections are stuck on in the 

 usual way with 30 per cent, alcohol, and when freed from paraffin are 

 treated as follows : — (1) Aqueous methyl-violet (1 per cent.) or gentian- 

 violet for 3-5 minutes ; (2) wash in distilled water ; (3) saturated 

 aqueous picric acid solution for 3-4 minutes ; (4) mop up with filter- 

 paper ; (5) anilin oil, to which 1 per thousand picric acid is added 

 until the- section is quite yellow and no more violet is given off; 

 (6) careful and prolonged washing in distilled water ; (7) Delatield's 

 hematoxylin for 5-8 minutes ; (8) careful washing in distilled water for 

 about 5 minutes ; (9) acetic acid, picric acid fuchsin (about 2-3 ccm. 

 picric acid fuchsin, to which one drop of 1 per cent, acetic acid solution 

 is added) for 3-5 minutes ; (10) immersion and dehydration in absolute 

 alcohol for 1/2-1 minute ; (11) xylol — xylol dammar. 



Staining the Karyochromatophilous Granules in Blood.J — Dr. A. 

 Plehn adopts the following method for staining granules in the blood 

 of persons residing in malarious districts. Dissolve hematoxylin 2 in 

 a mixture of alcohol, glycerin, and distilled water 100 each ; add acetic 

 acid 10, alum as much as may be necessary, and allow the mixture to 

 stand for 14-21 days ; then add a few grains of eosin. The prepara- 

 tions are fixed in absolute alcohol for at least one hour. They are 

 then placed in an air-tight capsule and stained for 8-12 hours. Only 

 water is used for decolorising. Finally they are dried and mounted in 

 balsam. 



Staining the Parasites of Leucocythaemic Blood.§ — Prof. M. Lowit 

 stains the parasites of leukhaemia by the following procedure. The dry 



* Miinchener Med. Wochenschr., 1900, No. 6. See Centralbl. Bakt. u. Par., 

 1" Abt, xxvii. (1900) pp. 57-9. 



t Centralbl. Bakt. u. Par., xxvii. (1900) pp. 534-5. 



t Deutseh. Med. Wocbenschr., 1899, No. 44. See Centralbl. Bakt. u. Par., 1" Abt., 

 xxvii. (1900) p. 627. § Centralbl, Bakt. u. Par., xxvii. (1900) pp. 462-6. 



Aug. 15th, 1900 2 N 



