GLYCERINATED POTATO 2OQ 



3. Sterilise in steam steriliser at 100 C. for 20 minutes on each 

 of three successive days. 



Resulting medium not translucent, but opaque and firm. 



B. Tuberculosis. 



Egg Medium (Lubenau). 



This modification of Dorset's egg medium (quod mde page 

 1 74) is preferred by some for the growth of the tubercle bacillus of 

 the human type. It consists in the addition of one part of 6 per 

 cent, glycerine in normal saline solution, to the egg mixture be- 

 tween steps 4 and 5. 



Glycerine Bouillon. 



1. Measure out nutrient bouillon, 1000 c.c. (vide page 163, 

 sections i to 6). 



2. Measure out glycerine, 60 c.c. ( = 6 per cent.), and add to 

 the bouillon. 



3. Tube, and sterilise as for bouillon. 



Glycerine Agar. 



1. Prepare nutrient agar (vide page 167, sections i to 8). 

 Measure out 1000 c.c. 



2. Measure out pure glycerine, 60 c.c. ( = 6 per cent.), and add 

 to the agar. 



3. Tube, and sterilise as for nutrient agar. 



Glycerine BIood=serum. 



1. Prepare blood-serum as described, page 168, sections i to 4. 



2. Add 5 per cent, pure glycerine. 



3. Complete as described above for ordinary blood-serum, sec- 

 tions 5 to 7. 



NOTE. Different percentages of glycerine from 4 per cent, to 

 8 per cent. are used for special purposes. Five per cent, is that 

 usually employed. 



Glycerinated Potato. 



1. Prepare ordinary potato wedges (vide page 174, sections 

 i to 4) . 



2. Soak the wedges in 25 per cent, solution of glycerine for 

 fifteen minutes. 



3. Moisten the cotton- wool pads at the bottom of the potato 

 tubes with a 25 per cent, solution of glycerine. 



4. Insert a wedge of potato in each tube and replug the tubes. 



5. Sterilise in the steamer at 100 C. for twenty minutes on 

 each of five consecutive days. 



14 



