88 



PHARMACEUTICAL BACTERIOLOGY. 



drop into place again; remove the cotton plug from test-tube by grasping it 

 between two fingers (back of fingers toward the test-tube) ; make the inocu- 

 lation (deep stab, shallow stab, or streak); withdraw needle; replace cotton 

 plug; hold needle in flame until glowing red. To prevent the sputtering of 

 the material on the end of the needle, hold near flame until dry and then heat 



2 



A 

 9 



f 



e 



a 



/o 



Fig. 41. — Square counting plate. Each area is one square centimeter. This is a 

 simple as well as staisfactory counting plate to be used in coimting Petri dish colonies and 

 tube colonies (tube roll cultures). By means of the Arabic numerals and the letters any 

 one of the loo areas can be located and designated for demonstration purposes. 



to redness. Singe free exposed end of the tube cotton plug in flame to kill 

 and remove microbes and spores on the outer part of the cotton. The 

 inoculated tubes are then numbered and incubated. In due time the cul- 

 tural characteristics are noted and the observations entered in a suitable 

 note-book. 



Subcultures may also be made in Petri dishes, on potatoes, in tubes con- 



