12 PRACTICAL BACTERIOLOGY. 



DEMONSTRATION V. 



Examination of Hanging Drop Cultures — Spores and 

 Spore Staining. 



1. Examine the hanging drop culture of Streptococ- 

 cus pyogenes made last day, with y 1 ^ oil-immersion lens; 

 at the margin of the drop long chains of streptococci 

 can be seen. 



2. Stain the hanging drop culture of Streptococcus 

 pyogenes, just examined. 



(o) Remove the oil carefully with blotting paper, 

 and then raising up the cover glass, clear away the 

 vaseline from its edges. 



(b) Dry, and pass film three times through the flame. 



(c) Stain the film by Gram's method. 



3. Examine the hanging drop culture of Bacillus 

 anthracis with the low and high dry lenses and the -^ 

 oil immersion. 



Note the long segmented threads at margin of 

 culture drop, and the presence in the rods of oval refract- 

 ing bodies — spores. 



4. Stain the hanging drop culture of Bacillus 

 anthracis with Loeffler's methylene blue, removing the 

 cover glass as described above, and clearing the film 

 before staining in 10% acetic acid. 



The spores remain unstained as oval refracting 

 bodies, both free and in the rods. 



