294 BACTERIOLOGY. 



sorb all water by gentle pressure with blotting-paper, 

 and finally, at very moderate heat, or with a small bel- 

 lows (Kiihne), dry the section completely on the slide. 



When dried clear up in xylol, and mount in xylol 

 balsam. 



(6) Transfer sections from alcohol to distilled water ; 

 from water to the dilute fuchsin solution, and gently 

 warm (about 50 C.) for fifteen to twenty minutes. 

 Transfer sections from the staining solution to the slide, 

 absorb all superfluous staining with blotting-paper, and 

 then treat them with 1 per cent, acetic acid from one- 

 half to three-quarters of a minute. Remove all trace 

 of acid with distilled water, absorb all water by gentle 

 pressure with blotting-paper, and then treat the sections 

 with absolute alcohol by allowing it to flow over them 

 drop by drop. For small sections three or four drops 

 are sufficient. Under no circumstances should the 

 alcohol be allowed to act for more than one-quarter of a 

 minute. Clear up in xylol and mount in xylol balsam. 



In method b the tissues are better preserved than in 

 a, where they are dried. 



Very good preparations are also obtained by the use 

 of Lreffler's alkaline methylene-blue, if care be taken 

 not to stain for too long a time or to decolorize with 

 alcohol too energetically. 



No method of contrast-stain for this organism in tis- 

 sues has been devised. 



In properly stained tissues the bacilli will be found 

 most numerous in the centre of the nodules, becoming 

 fewer as we approach the periphery. They usually lie 

 between the cells, but at times may be seen almost 

 filling some of the epithelial cells, of which the nodule 

 contains more or less. They are always present in these 



