NUTRIENT GELATINE 37 



tion is added to produce a deep purple coloration. Fermentation 

 tubes are filled with a measured quantity of the liquid, and steril- 

 ised in the Koch at 100' C. on three consecutive days. 



9. Drigalski and Conradi's medium^ — 



Prepare as follows : — {a) Agar solution ; {b) Litmus solution 

 {a) Put 3 lb. finely-minced beef into 2 litres of water, and allow to 

 stand till following day. Press out the "■ Fleischwasser" boil for 

 one hour, filter, add 20 gr. dry VVitte's peptone (pep. siccum), 

 20 gr. neutrose, and 10 gr. NaCl ; boil again for one hour, and 

 add 60 gr. finest bar agar ; boil for three hours, make faintly 

 alkaline to litmus, filter, and boil for half an hour. (J?) Take 260 

 ccm. of Kubel and Tiemann's litmus solution, boil for ten minutes, 

 add 30 gr. chemically pure milk-sugar, and boil for fifteen minutes. 

 Well mix a and b, and re-establish the faintly alkaline reaction ; 

 add 4 ccm. of a hot sterile solution of 10 per cent anhydrous soda 

 and 20 ccm. of freshly-prepared solution of i gr. crystal violet 

 B. (Hochst) in 100 ccm. of warm distilled water. The authors 

 give many details of manipulation and technique, for which the 

 original memoir should be consulted. 



10. Nutrient grelatine {to make i litre) — 



Take half a litre of liquid peptone prepared as above and filter 

 cold. Place in clean enamelled saucepan, bring slowly up to boiling 

 point, and boil for five minutes. Filter, and make alkaline to 

 litmus with caustic soda solution. Very exact neutralisation is not 

 necessary at this point, as the whole medium will subsequently be 

 made neutral to phenolphthalein. Add half a litre of beef bouillon 

 prepared as above up to and including the first filtration, and 5 

 grammes of common salt. Bring up to boiling point, boil for ten 

 minutes, filter hot, and make up to i litre with distilled water. 

 Remove the flame, and add slowly no grammes (winter) or 120 

 grammes (summer) of best gold label gelatine, stirring constantly 

 until dissolved. Replace flame, and bring up again to boiling 

 point. Neutralise to phenolphthalein in the manner described 

 under the head of neutralisation of media. Boil for five minutes, 

 cool down to 60', add the white of one &%% mixed with 60 cc of 

 distilled water, and thoroughly incorporate by stirring. Steam for 

 one hour in Koch's steriliser. Filter hot through double filter 

 paper, run into tubes, and sterilise by intermittent heating in the 

 Koch steriliser at 100° for thirty minutes on three successive days. 

 » Zeitfur Hyg., 39, 1902, p. 283 



