Cultivation 545 



Horse-meat infusion (3 pounds of horse meat 



to 2 liters of water) 2 liters 



Witte's peptone 20 grams 



Nutrose 20 grams 



Sodium chloride 10 grams 



Agar-agar 60 grams 



Litmus solution (Kubel and Tiemann) 260 c.c. 



Lactose 30 grams 



Crystal-violet solution (0.01 per cent.) 20 c.c. 



Before adding the crystal-violet solution render feebly alkaline to 

 litmus (about 0.04 per cent, of pure soda). 



Colon colonies upon this medium appear in fourteen to sixteen hours 

 to be red and opaque. Typhoid colonies blue or violet, transparent 

 and drop-like. 



Beckman * modifies the preparation, making it as follows : 



"(a) Add i liter of water to 680 grams of finely chopped lean beef 

 and place in the cold for twenty-four hours. Express the juice and 

 make up to i liter. Coagulate the albumin, either by boiling for ten 

 minutes or by heating to 120 C. in the autoclave. Filter. Add 10 

 grams of Witte's peptone, 10 grams of nutrose, and 5 grams of sodium 

 chloride. Heat in the autoclave at a temperature of 120 C. for thirty 

 minutes, or boil vigorously for fifteen minutes. Render slightly alkaline 

 to litmus-paper. Filter. Add 30 grams of agar. Heat in the auto- 

 clave at a temperature of 1 20 C. for one-half hour, or heat over the gas- 

 flame until the agar is dissolved. Render slightly alkaline to litmus- 

 paper while hot, if necessary. Filter through glass wool into a sterile 

 vessel. 



" (6) To 130 c.c. of litmus solution (Kubel and Tiemann' s) add 15 

 grams of chemically pure lactose. Boil for ten minutes. 



" (c) Mix (a) and (6) while hot. Render slightly alkaline to litmus, 

 if necessary. To the mixture add 2 c.c. of hot sterile solution of 10 per 

 cent, sodium hydrate in distilled water and 10 c.c. of a fresh solution of 

 Hochst's crystal violet (o.i gram of crystal violet to 100 c.c. of sterile 

 water) . 



" The medium is now poured into Petri dishes and is of a deep pur- 

 ple color. So much water of condensation forms on the solidified surface 

 that it is an advantage to use porous clay covers (Hill) for the Petri 

 dishes instead of the ordinary glass covers. The medium keeps well 

 but dries up rapidly." 



A very ingenious method of isolating the typhoid and 

 colon bacilli from drinking water has been suggested by 

 Starkey,f who uses a tubular labyrinth of glass into which 

 a nutrient medium, ordinary bouillon containing 0.05 per 

 cent, of carbolic acid, or Pariette's bouillon: 



i. Measure out pure hydrochloric acid, 4 c.c., and add it to carbolic 

 acid solution (5 per cent.), 100 c.c. Allow the solution to 

 stand at least a few days before use. 



* See F. F. Wesbrook, "Jour. Infectious Diseases," May, 1905, Sup- 

 plement, No. i, p. 319. 



f " Amer. Jour. Med. Sci.," July, 1906, cxxxn, No. i, No. 412, p. 109. 

 35 



