APPENDIX 357 



Reaction. Phenolphthalein is used as indicator. 



Titrate media while hot with N/20 NaOH and adjust 

 the reaction if necessary. All media should have a +10 

 reaction Fuller's scale unless otherwise stated in the direc- 

 tions. 



Distribution of Work. It may be desirable to have 

 students work in groups in preparing media. The fol- 

 lowing plan has worked satisfactorily: 



Students may work in groups of five, one of the groups 

 preparing a sufficient quantity of medium for himself and_the 

 other four members of the group, dividing the work up as 

 follows : 



One student prepare agar shakes and litmus milk. 



One student prepare gelatin. 



One- student prepare litmus lactose agar. 



One student prepare litmus lactose bile. 



One student prepare Dunham's solution and nitrate 

 peptone solution. , 



In this arrangement each student must furnish the re- 

 spective sterile glassware sufficient for containing the various 

 necessary media, to the student preparing each medium. 



Each student of the group must so plan his work that the 

 medium he prepares will be finished, sterilized and ready for 

 use at the same time as those of the remaining members of 

 his group. 



Media. Litmus lactose agar shake. 



1. 2% washed agar. 

 2% peptone. 

 2% lactose. 



2% azolitmin. 



500 c.c. meat infusion. 



500 c.c. distilled water. 



Method. 1. Strain the meat infusion through a piece 

 of clean cheese-cloth. 



2. Place the washed agar in the distilled water, weigh, 



