108 



tend to diminish the sharp contrast that is desired. The 

 specimens after staining with the eosine is thoroughly 

 washed with water and examined under the microscope. 

 It should show the deeply stained violet bacilli on a light 

 pink back-ground. 



Weigert's picro-carmine solution, or Bismarck brown, 

 can be also used for contrast colors. The Gram's method 

 is applicable to many pathogenic bacilli and to most 

 micrococci. A notable exception among the latter is the 

 gonococcus. The other important organisms that do not 

 stain with this method are the bacillus of typhoid fever, 

 of Asiatic cholera, of glanders, of chicken cholera, of 

 rabbit septicaemia; also Friedlaender's pneumo-bacillus, 

 and the spirillum of recurrent fever. 



The following synopsis of the staining methods for 

 streak preparations will be of service: 



Cover glass preparation. 



Air-dried. 



3 x through tlame. 



Simple slain : Gram?s stain : 



Dilute anilin dye Anilin water gentian violet 



(i to | min.). (10 10 15 min.; if hot, 2 to 



Water (and examine). 5 inin.). 

 Air-dried. Water. 



Canada balsam. Iodine in potassium iodide 



(| to 1 to 3 min.). 

 Water. 

 Alcohol. 



Water (and examine). 

 Contrast color (eosine or 



picrocarmine, few sec.). 

 Water (and examine). 

 Air dried. 

 Canada balsam. 



The hanging-drop examination and the streak prepa- 

 rations stained by the simple and double method as 



