110 A MANUAL OF BACTERIOLOGY 



as follows : Immerse in (1) xylol for one or two minutes, 

 drain ; (2) absolute alcohol one to two minutes to remove 

 the xylol, drain ; (3) distilled water. They are now 

 ready for staining, and are to be flooded with the staining 

 solution or immersed in it, and after staining they are 

 treated in the same manner, but in the reverse order, viz. 

 (1) distilled water; (2) methylated spirit; (3) absolute 

 alcohol ; (4) xylol. On being removed 

 from the xylol the slide is drained for a 

 few seconds, a drop of xylol balsam is then 

 put on, and the section covered with a 

 clean cover-glass. Glass pots (Fig. 20} 

 filled with the alcohol, xylol, etc., are 

 convenient for the treatment of paraffin 

 sections, the slide with the section upon it 

 being immersed in the fluid. 



Section Staining 



When Gram's method is applicable it 

 FIG. 20. Glass pot , , ., 



for clearing, etc. gives by far the best results, and should 



always be employed. If, however, the 

 organisms are decolorised in Gram's process some other 

 method must be adopted. One of the best is to 

 stain for from ten minutes to six or eight hours in 

 Lomer's methylene blue. Fresh easily staining organisms 

 will be sufficiently stained in ten or fifteen minutes, but 

 when the organism is difficult to stain, as glanders, six to 

 eight hours may not be too long a time. Warming intensi- 

 fies the staining properties of all staining solutions ; for 

 frozen sections the watch-glass of stain may be warmed 

 on a sand-bath or asbestos cardboard, or in the blood-heat 

 incubator. Sections on the slide may be flooded with the 

 stain and warmed on a piece of asbestos cardboard placed 

 over a Bunsen flame, or a penny may be heated in the 



