150 THE AMERICAN MONTHLY [May 



or any otlier medium which re(|uii»^s a meat infusion for 

 its nutritive base. (2) Tliat the a«;ar sliould be cut up in 

 small pieces and dissolved in a liquid which contains no 

 coagulable material before it is added to the bouillon. 

 This is done by using the pr()[)()rtion of five grams of 

 agar, finely chopped, to 100 c. c. of water and boiling- in 

 an agate iron dish over a direct flame with constant stir- 

 ring. I have found, however, that it is more satisfactory 

 to boil the agar in a closed water bath. Tiiis takes not 

 to exceed twenty minutes longer and as there is no dan- 

 ger of the agar burning the stirring and constant atten- 

 tion required when it is dissolved over a flame is unnec- 

 essary. By this method the agar is completely dissolved 

 and a medium of a known consistency can always be made. 



In 1892 Schiilt/.,* of the Johns Hopkins Hospital, de- 

 scribed a rapid method of making agar which requires 

 hut one hour for the whole process. For this he uses 

 meat extract which gives a medium favorable for the 

 growth of some organisms but not for others. He also 

 gives a method by which the agar may be made from 

 meat infusion taking but an hour and a half. 



The following method of preparing media has proved 

 very satisfactory and in my hands more so than the one 

 described by Schnltz althougli his ]>roccss has many ad- 

 vantages. 



The 'preparation of peptonized boui//on. — To 1(M(() grams 

 of finely chop[>ed or ground meat (beef or veal) add 2000 

 c. c. of distilled water. Put in an agate iron dish and 

 heat in a water bath at a temperature of from 60° to 65° 

 C for two hours or allow it to macerate in a cool place 

 for 24 hours. Strain through a coarse cloth and bring 

 the amount of liquid uj) to 20(K) c. c. by adding water if 

 necessary. To this infusion add I per cent pe^jtone and 



*A Ivapid Method of Making Agar-agar. By .John L. Schiiltz. John's 

 Hopkins Ho.spiUil Hulletiu,X(». :>4, July— Aug., 1H!)2. 



