130 BIOLOGY AND TECHNIQUE 



When celloidin sections are stained in this way ninety-five per cent alcohol 

 should be substituted for the absolute. A number of other staining solutions 

 may be used in the same way, aqueous fuchsin or aqueous gentian-violet 

 yielding good result. 



Nicolle advises the use of a ten per cent aqueous solution of 

 tannic acid for a few seconds after washing with the acetic acid. 



Sections may also be stained by placing them over night into a 

 dilute Giemsa solution (one drop to each c.c. of distilled water). 

 When so stained the sections must not be run through the weaker 

 alcohols but must be rapidly differentiated in absolute alcohol. 



METHOD OF STAINING GRAM-POSITIVE BACTERIA IN TISSUE SECTIONS. 

 Celloidin Sections. After fixing section to the slide by pressure with a filter 

 paper or ?by ether vapor, cover with anilin-water gentian-violet five minutes. 



Pour off excess of stain and cover with Gram's iodin solution for two 

 minutes. Decolorize with ninety-five per cent alcohol until no more color 

 comes out. 



Stain quickly with eosin-alcohol (ninety-five per cent alcohol to which 

 enough eosin has been added to give a transparent pink color; about 1:15). 

 Clear in eosin-oil of origanum (oil of origanum, 25 c.c. and eosin alcohol, 

 as above, about 3 c.c.). Blot and mount in balsam. 



Paraffin Sections. Stain with anilin-water gentian-violet five to ten 

 minutes. 



Wash in water. 



Cover with Gram's iodin solution one minute. 



Wash in water. 



Decolorize with absolute alcohol until no more color comes out. 



Clear in xylol. 



Mount in balsam. 



Gram-Weigert Method. (For celloidin sections.) Stain for one-half 

 hour in the following freshly filtered solution: 



Carmine 3.5 gra ms. 



Saturated aqueous solution of lithium carbonate 100 c.c. 



Dehydrate in ninety-five per cent alcohol. 



Stick section to slide with ether vapor. 



Stain in anilin-water gentian- violet for five to fifteen minutes (or in a 

 saturated solution of aqueous crystal violet diluted with water one to ten, 

 five to fifteen minutes). 



Wash in physiological salt solution. 



Cover with Gram's iodin solution one to two minutes. 



Wash in water and blot. 



39 Weigert, Fortschr. d, Med., v, 1887, 



