3 o8 



LABORATORY WORK. 



Forceps Common and Cornet forceps. 

 Microscope with 1/12 immersion lens and plenty of slides 

 and cover-glasses. 



MATERIALS. 



Peptone (Witte) 

 Salt 



Beef extract 

 Gelatin Gold label 

 Agar-agar 



Litmus, dry in cubes 

 Absorbent cotton 

 Fuchsin 



Dextrose, lactose, and 

 saccharose 



Normal NaOH and Normal 



HC1. 



Phenolphthalein 

 Alcohol 



Corrosive sublimate 

 NaOH 

 HCI 



Azolitmin 

 Methylene blue 

 Common cotton, good quality 



No. i. Washing and Sterilizing Glassware. All glass- 

 ware must be thoroughly washed in hot water and soap. 

 New glassware should first be treated with i per cent. HCI. 

 Used glassware, containing remains of gelatin or agar, should 

 first be boiled in water containing powdered soap or sal soda. 

 Follow this with thorough washing in hot water, rinsing in 

 cold water and draining. 



To begin with, the student may wash 50 test-tubes, 2 one- 

 liter flasks, one dozen Petri dishes and several i c.c. pipettes. 

 After drying, place the pipettes in glass holders or a metal 

 box, plug the test-tubes and flasks tightly with cotton and 

 place these -with the Petri dishes in the sterilizing oven. 

 Heat for one hour at 310 F. (155 C.) for one hour. All 

 glassware should be subsequently sterilized in the same 

 way before using. 



No. 2. Preparation of Agar Culture Medium and Bouillon. 

 Measure out the following: 



Water i liter 



Liebig's extract of beef 3 grams 



Common salt 5 grams 



Peptone 10 grams 



a. Divide in two lots, set one-half aside (see below) ; 

 place the other half in a stew-pan and carefully weigh the 

 dish and its contents, noting the combined weight for future 

 use. Dissolve the mixture at about i 50 F. (6oC.). Add 

 6 grams of agar-agar (1.2 percent.), cut into small pieces, and 

 dissolve by heat. It takes considerable heat to dissolve the 

 agar and may require boiling. Boil till the agar is com- 

 pletely dissolved and then replace the water that has evaporated by adding 

 cold water till the original weight has been restored. 



FIG 56. 

 i c.c. pipettes 

 inclosed in 

 glass tubes for 

 sterilizing. 



