8 PRACTICAL BACTERIOLOGY. 



3. Prepare cover glass films from the gelatine culture 

 of Streptococcus pyogenes, and also from the liquefying 

 gelatine culture of Staphylococcus pyogenes aureus. 

 Stain them according to Gram's method as follows: 



(a) Place the films in alcohol one to two minutes. 



(6) Without drying, transfer to anilin gentian violet 

 for two minutes. 



(c) Rinse in water or .6% saline solution, and then 

 place for one-half to one minute in Gram's iodine solu- 

 tion, (Iodine 1 part, Potassium iodide 2 parts, Water 

 300 parts). 



(d) Rinse in water, end then in alcohol, till no more 

 stain comes away. 



(e) Wash in water, dry and mount in Canada balsam. 



