APPENDIX 447 



The reagents are best kept in dropping-bottles. 



The staining of sections on slides is exactly as for those on cover-glasses. Cop- 

 lin's staining jars are very convenient for use in staining slides. 



Where the cover-glass method is used, staining by Gram's method, acid-fast stain- 

 ing, capsule staining, etc., may be carried out as for bacterial preparations. 



For staining Gram-positive bacteria in sections, the Gram method as for bacterial 

 preparations, using dilute carbol fuchsin as a counterstain, gives good results. 



For Gram-negative bacteria stain with thionin as for blood preparations (ten to 

 twenty minutes). Then differentiate in i to 500 acetic acid solution for ten to 

 twenty seconds, wash with water, then with 95% alcohol, and quickly through abso- 

 lute alcohol and xylol. 



Nicolle's Method. i. Stain with Loffler's methylene blue ten to fifteen minutes. 



2. Differentiate in i to 500 acetic acid ten to twenty seconds. 



3. Place in i% solution of tannin for a few seconds (fixes color). 



4. Wash in water, then into 95% alcohol, absolute alcohol, xylol, and balsam. 



WEIGERT'S IRON ILEMATOXYLIN 



Solution I 



Haematoxylin, i gram. 



Alcohol (95%), 100 c.c. 



This must be allowed to ripen for some days and does not keep over six months. 



Solution H 



Liq. Ferri sesquichlor. sp. gr. 1.124 (about 10%) 4 c.c. 



HCL, i c.c. 



Water, 100 c.c. 



Mix equal parts of number one and number two. The mixture only keeps about 

 three days. The HC1 prevents overstaining. 



This stain followed by Van Giesen's stain gives more perfect results than any 

 common method of staining. The iron haematoxylin intensifies the sharpness of 

 the Van Geisen differentiation. 



Other iron haematoxylin stains are given under staining for protozoa. 



Van Giesen's Stain. Take of i% aqueous solution acid fuchsin from 5 to 15 

 c.c. Saturated aqueous solution picric acid 100 c.c. The method of using is to first 

 stain with haematoxylin in the usual way. Then pour on the picric-acid fuchsin 

 solution and allow to stain for one to five minutes. Wash, pass through alcohols 

 and xylol and mount in balsam. 



Connective-tissue fibers, axis cylinders, and ganglion cells are stained a bright 

 garnet red. Myelin, muscle fibers, and cells generally are stained yellow. Nuclear 

 staining is that of haematoxylin. The stronger stain is used for nerve tissue; the 

 weaker, for demonstrating connective tissue in tumors. 



Levaditi's Method. Take small pieces of tissue, about 2 mm. in thickness, and 

 harden in 10% formalin for twenty-four hours and then in alcohol for the same pe- 

 riod; then wash in water for a short period. They are stained in a freshly made solu- 

 tion of silver nitrate 1.5% for three successive days, changing the solution each day, 



