242 



BACTERIOLOGICAL METHODS 



tubes. After making the plants, the loops or spoons are flamed as 

 already described. 



After an experiment is finished the date and any necessary 

 details can be marked on one of the broth tubes and the rack 

 placed in the incubator at 37° C. for 48 hr. At the end of this 

 time the results are recorded on a chart especially devised for the 

 purpose. (See Table III.) 



Determining the Coefficient. — After a large number of experi- 

 ments, we have concluded that the method employed by theLancet 



Fig. 87. — Device for holding and flaming inoculating loops. — {Andcrsonb' McClinlic, 

 Hygiene Laboratory Bulletin No. 82, U. S. Public Health Service.) 



Commission, with certain modifications, is the best one for de- 

 termining the coef&cient, i.e., the mean between the strength and 

 time coefficients. 



In performing the test, plants are made every 2I-2 min. up to 

 and including 15 min. To determine the coeihcient, the figure 

 representing the degree of dilution of the weakest strength of the 

 disinfectant that kills within 2^ min. is divided by the figure 



