EXAMINATION OF BACTERIA WITH THE MICROSCOPE. 45 



glass preparations which may be prepared in the usual way 

 from material supposed to contain spores. 



(a) After drying the smear on the cover-glass, and fixation 

 with heat by passing through the flame three times, use as a stain 

 anihne- water fuchsin. 



(b) Heat until the JDreparation begins to boil; remove for a 

 minute; heat again, and again remove; repeat this process six 

 times. 



(c) Wash in a weak solution of acetic or hydrochloric acid 

 for a few seconds to a minute. Some spores are quickly de- 

 colorized by I per cent, acetic acid; others may keep the stain 

 when subjected to 3 per cent, hydrochloric acid alcohol for a 

 minute. 



(d) Wash in water. 



(e) Stain with watery solution of methylene^blue half a 

 minute. 



(/) Wash. 



(g) Dry. 



(h) Balsam. * 



The spores are intensely stained by the fuchsin. The stain 

 is removed from everything except the spores by the acid. 

 The methylene-blue solution stains the bodies of the bacteria, 

 the spores remaining brilliant .red. There are various other 

 methods for staining spores, but this procedure gives good 

 results. The principle is the same as in staining the tubercle 

 bacillus, except that more pains are needed to impregnate spores 

 with the dye. 



Staining of Capsules. — The capsules which many bacteria 

 possess appear to be made of gelatinous substance, which is 

 dif£cult to stain. 



Method of Welch. — (a) Cover-glass preparations are made 

 in the usual manner. Pour glacial acetic acid over the film. 



(b) After a few seconds, replace with aniline-water gentian- 

 violet, without washing in water. Change the stain several 



