82 BIOLOGY AND TECHNIQUE 



after the last tube has been inoculated a subculture is made from the 

 first tube of the series {i.e., 2}^ minutes after this first tube was inocu- 

 lated) and from the other tubes in order at 15-second intervals. Fifteen 

 seconds after this first series of subcultures is completed a second series 

 of subculturesis begun whichwillgivethe result of a 5-minute exposureto 

 the antiseptic and the subinoculations continued at 15-second intervals 

 until all dilutions have been tested for fifteen minutes. If the strength 

 of the antiseptic is known approximately subcultures of the lower dilu- 

 tions for the longer periods may be omitted. It is convenient to have 

 an assistant at hand to call time and to label the subcultures as soon as 

 made. The tubes may, however, be placed in order in suitable racks 



DETERMINATION OF THE CARBOLIC-ACID COEFFICIENT 

 OF A DISINFECTANT. 



(Anderson and McClintic) 



Name "A" 



Temperature of Medication 20° C. 



Culture Used B. Typhosus 24-hr., Extract Broth, Filtered 



Proportion of Culture and Disinfectant 0.1 c.c. + 5 c.c. 



Organic Matter, None; Kind, None; Amount, None. 



Subculture Media Standard Extract Broth 



Reaction + 1.5 



Quantity in Each Tube 10 c.c. 



