SPECIAL MEDIA. 103 



mixture consists of one part of neutral meat-infusion 

 bouillon containing 1 per cent, of grape-sugar, and three 

 parts of blood-serum. This mixture is placed in test- 

 tubes, sterilized, and solidified in exactly the way given 

 for blood-serum. It requires for its solidification a 

 somewhat higher temperature and a longer exposure to 

 this temperature than does blood-serum to which no 

 bouillon has been added. (See also the Councilman- 

 Mai lory method.) 



GuarniarVs agar-gelatin : 



Meat infusion 950 c.c. 



Sodium chloride 5 grammes. 



Peptone 25-30 " 



Gelatin 40-60 " 



Agar-agar 3-4 " 



Water . 50 c.c. 



The point in the preparation of this medium is its 

 reaction, which should be exactly neutral. 



The list of special media is too great to be given in a 

 work of this size. Their description must be seen in 

 the original. Those that have been given above will 

 suffice for obtaining a clear understanding of the prin- 

 ciples of the work. 



NOTE. The term " meat-infusion" always implies a 

 watery extract of meat made by mixing 500 grammes of 

 finely chopped lean meat and 1 litre of water together, 

 and allowing them to stand in a cool place for twenty- 

 four hours. At the end of this time the fluid portion is 

 strained off through a coarse towel. This represents 

 the infusion. 



