150 THE AMERICAN MONTHLY [May 



or any other medium which requires a meat infusion for 

 its nutritive base. (2) That the a^ar shoukl 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 proportion 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. This takes not 

 to exceed twenty minutes longer aad 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 Schultz,* of the Johns Hopkins Hospital, de- 

 scribed a rapid method of making agar which requires 

 hut one hour for the whole process. F'or 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 Schultz although his process has many nd- 

 vantages. 



The 'preparation of peptonized bouillon. — To 1000 grams 

 of finely chopped 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 up to 2000 c. c. by adding water if 

 necessary. To this infusion add | per cent peptone and 



*A Rapid Method of Making Agar-agar. By John L. Sdiultz. John's 

 Hopkins Hospital Bulletiu,No. 24, July— Aug., 1892. 



