MEDICAL BACTERIOLOGY 



From i : 900 to i : 1800 by a difference of 100. 



From i : 800 to 1 13200 by a difference of 200. 

 And so on if higher dilutions are necessary. 



It is important that the cylinders used for making the dilutions be correctly 

 graduated, as we have found disregard of this factor an important source of 

 error. It is preferable to use standardized cylinders and pipettes, and we recom- 

 mend that they be used whenever possible. They, of course, should be per- 

 fectly clean. For making the dilutions in accordance with the above scheme 

 we have found the following tables of much service: 



TABLE 15 (FOR DILUTIONS). STOCK 5 PER CENT. SOLUTION 

 (5 cc. disinfectant + 95 cc. distilled water = solution A) 



