40 MANUAL or BACTERIOLOGY. 



filled with water. Loffler's solution of methylene-blue serves 

 very well. 



By this process most bacteria are stained; also the nuclei 

 of cells; frequently, also, certain granules contained within 

 some cells (German, Masizellen), which may easily be mistaken 

 for bacteria by the inexperienced (basophihc granules). 



(a) Place the section in the staining solution from two to 

 five minutes. 



(b) Wash in water. 



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

 one minute. 



(d) Alcohol, one to two minutes ; change to absolute alcohol. 

 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 remove aniline 

 colors. It has the disadvantage of not clearing when the sHghtest 

 trace of water is present; dehydration in alcohol must, there- 

 fore, be complete. The section should be removed from the 

 xylol as soon as it is cleared; otherwise wrinkling occurs. 



(/) 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 sUde is managed best with 

 a spatula or section-lifter. 



The above statements apply to frozen sections or to sections 

 imbedded in celloidin. Paraffin sections are preferably at- 

 tached 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 sHde may be placed in a large dish 

 full of staining fluid. (See page 37.) Celloidin sections may 

 also be stained on the sHde. If the section be well spread and 

 flattened thoroughly with blotting-paper, it will usually adhere 



