252 THE JOURNAL OF PHARMACOIyOGY. 



The use of powdered agar, which has been in the market for two 

 or three years, because of its ready sokibihty, simpHfies the process and 

 greatly shortens the time required in the preparation of the medium ; 

 but for some reason, doubtless because of the scant notice which has 

 been given to the matter in the literature, it does not yet seem to have 

 come into general use. To call attention to the powdered form, and 

 report a method for obviating the appearance of secondary precipitates 

 in the tubes, on sterilization, was the object of a paper by the writer pub- 

 lished in the first number of the Journal of Applied Microscopy. 



The method then described materially lessened the time and labor 

 recpured in the preparation of agar aud gave a perfectly transparent 

 product. Subsequent efforts, aided by d suggestion obtained from an 

 article by Dr. Ravenel, in the June number of the Journal, have enabled 

 us to shorten the time limits from two and one-half hours to one hour, 

 counting from the time of the receipt of the meat in the laboratory until 

 the last drop of the completed medium has passed through the filter, and 

 yet obtained average results ; while by deferring filtration until after 

 the first sterilization a perfectly transparent medium is obtained. In 

 the latter event from half to three-quarters of an hour suffices for the 

 initial preparation, exclusive of the time required for sterilization in 

 hulk, but a half hour more is required on the following day for re- 

 heating and filtering. The process is as follows: 



Rub up lo grams each of powdered agar and Witte's pow^dered pep- 

 tone, and 5 grams of sodium chloride, in a porcelain-lined saucepan, with 

 just sufficient water to thoroughly moisten the powder and form a thin 

 paste; add gradually, while stirring the mixture, 500 cc. of water; place 

 on a gas stove, interposing a piece of asbestos board or wire gauze 

 between the saucepan and flame, and heat the mixture until the agar is 

 dissolved, stirring occasionally to prevent burning on the bottom 

 of the dish. If the paste made with cold water is properly rubbed up,%o 

 as to break down all the lumps and moisten all the agar, solution will be 

 practically complete by the time the boiling point has been reached, so 

 that two or three minutes* brisk boiling suffices. 



With the aid of a meat press, extract the juice from 500 grams (one 

 pound) of lean meat, and add the juice to 500 cc. of water. Mix this 

 "fresh water" with the agar solution — which now should have cooled 

 sufficiently not to coagulate the albumin in the fresh water, but still be 

 hot enough to remain fluid — and carefully neutralize with a four per 

 cent, solution of caustic soda. 



After neutralization boil the mixture until all the coagulable albu- 

 min in the fresh-water has been coagulatetl and comes to the surface, 

 leaving a clear fluid beneath. Again test the reaction, and, if need be. 



