Staining 



181 



by Kolle * that the tissue be saturated with a mixture of 

 glycerin, i part ; gelatin, 2 parts ; and water, 3 parts ; cemented 

 to a cork or block of wood, hardened in absolute alcohol, 

 and cut as usual for celloidin with a knife wet with alcohol. 



Staining. Simple Method. For ordinary work the 

 following simple method can be recommended: After the 

 sections are cut and cemented to the slide, the paraffin 

 and celloidin should be removed by appropriate solvents. 

 The sections are immersed in the ordinary aqueous solution 

 of the anilin stain and allowed to remain about five minutes, 

 next washed in water for several minutes, then decolorized 

 in 0.5 to i per cent, acetic acid solution. The acid removes the 

 stain from the tissues, but ultimately from the bacteria as 

 well, so that one must watch carefully, and so soon as the 

 color has almost disappeared from the sections, they must 

 be removed and transferred to absolute alcohol. At this 

 point the process may be interrupted to allow the tissue 

 elements to be countercolored with alum-carmin or any 

 stain not requiring acid for differentiation, after which the 

 sections are dehydrated in absolute alcohol, cleared in 

 xylol, and mounted in Canada balsam. 



The greater number of applications can be made by 

 simply dropping the reagents upon the slide while held in 

 the fingers. Where expos- 

 ure to the reagents is to be 

 prolonged, the Coplin jar 

 (Fig- 35) or some more 

 capacious device must be 

 employed. 



Pfeiffer's Method. The 

 sections are stained for one- 

 half hour in diluted Ziehl's 

 carbol-fuchsin (pp. 187 and 

 716), then transferred to 

 absolute alcohol made feeb- 

 ly acid with acetic acid. 

 The sections must be care- 



fully watched, and so soon 35 ._Coplin's staining jar. 



as the original, almost 



black-red color gives place to a red-violet color they are 

 removed to xylol, to be cleared preparatory to mounting 

 in balsam. 



* Flugge's " Die Mikroorganismen." vol. i, page 534. 



CROSS-SECTION 

 SHOWING SLIDES 

 M POSITION, 



