52 MANUAL OF BACTERIOLOGY. 



(c) Place in a watery solution of acetic acid, .1 per cent., 

 for one minute. 



(d) Alcohol, one to two minutes; change to absolute al- 

 cohol. Touch the sections to blotting-paper to remove the 

 superfluous alcohol. 



(e) Xylol until clear; xylol is to be preferred to other 

 clearing agents, like oil of cloves, most of which slowly re- 

 move aniline colors. It has the disadvantage of not clearing 

 when the slightest trace of water is present ; dehydration in 

 alcohol must, therefore, be complete. The section should 

 be removed from the xylol as soon as it is cleared ; otherwise 

 wrinkling occurs. 



(f) The section is placed upon a glass slide; a drop of 

 Canada balsam is placed upon it and then a cover-glass. 

 The Canada balsam should be dissolved in xylol. 



The section is to be manipulated with straight or bent 

 needles. The removal from xylol to the glass slide is man- 

 aged best with a spatula or section-lifter. 



The above statements apply to frozen sections or to sec- 

 tions imbedded in celloidin. Paraffin sections are preferably 

 attached to the slide with glycerin-albumen. The different 

 steps in the process follow in the same order. The stain 

 may be poured on the slide, or the slide may be placed in 

 a large dish full of staining fluid. (See page 49.) Celloidin 

 sections may also be stained on the slide. If the section be 

 well spread and flattened thoroughly with blotting-paper, 

 it will usually adhere to the slide, and is less likely to 

 wrinkle. It must not be allowed to dry. 



Gram's Method may be applied to the staining of sec- 

 tions of tissues as well as to smears upon cover-glasses. 



(a) Place the section in aniline-water gentian-violet, 

 one to five minutes. 



(&) Rinse briefly in water. 



(c) Iodine solution (see page 42), one and one-half 

 minutes. 



