Xn. STAINING SPORES, BSPBOIALLY ANTHRAX 

 SPORES. 



To obtain very beautiful preparations of anthrax spores the fol- 

 lowing method is recommended : Make hanging-drop cultures in bouil- 

 lon from the heart's blood of an anthrax mouse (or other experiment 

 animal), using a scarcely- visible amount of blood; place the incu- 

 bator at 35 to 37 degrees G. ; in a few hours the well-known beauti- 

 ful threads and ropes are formed, and after from twenty-four to 

 forty-eight hours these threads aj-e usually filled with spores (PI. I, 

 Figs. 1, 2). The cover-glasses are then removed from the slide (first 

 lifting one edge with a knife-blade), dried in the air, the vaseline 

 washed off with xylol, and stained as follows: 



1. Fix the dried preparation. 



2. Float 'Tjutter" side down, on the surface of aniline- 

 water-fuchsin-solution (See III, foot-note 2, a and b, sub- 

 stituting fuchsin for gentian-violet); heat untU a delicate 

 vapor arises and continue this for from five to six hours 

 (if much evaporation occurs more aniline-water must be 

 added). It is better to leave the preparation in the dye 

 four or five hours after it has cooled. 



3. Decolorize in 25 per cent. HNO3 about five sec- 

 onds. 



4. Carefully wash in alcohol until no more color comes 

 away, and place for a short time in distilled water. 



5. Contrast stain in watery methylene-blue solution, 

 five minutes. 



6. Wash carefully in water, mount, etc., and examine. 

 If the preparation is satisfactory: 



7. Dry and mount in balsam. 



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