CHANGES m FEESH BEEF DUfelNGt COLD STORAGE. 9 



ter one hind quarter was cut from the carcass, Avrapped in cheese- 

 cloth previously soaked in a solution of bichlorid of mercury 

 (1-1,000) and then in dry cheesecloth and paper, and was at once 

 transported to the laboratory by means of a motor truck, the trip 

 requiring about half an hour. 



Preparation of samples. — At the laboratory the hind quarter was 

 transferred at once to a small bacteriological workroom, the floor, 

 walls, and ceiling of which had been sprayed a short time previously 

 with a disinfectant solution. Large plugs of meat, approximating 

 3 to 4 inch cubes, were cut from the muscular tissue, avoiding con- 

 nective tissue and fat as much as possible. Sterile instruments 

 were used in taking the samples and great care was exercised to 

 make this procedure as nearly aseptic as possible. In taking the 

 samples the outer portions of the hind quarter which had come in 

 contact with the bichlorid gauze were of course rejected, these por- 

 tions being trimmed away. The samples, which Aveighed from 274 

 to 512 grams, were immediately transferred to sterile crystallizing 

 dishes fitted with glass covers. The dishes were then Aveighed and 

 the covers sealed with adhesiA^e tape and over the tape Avere placed 

 strips of tin foil. This was done for the double purpose of preA^ent- 

 ing evaporation and bacterial contamination from the outside. The 

 dishes containing the samples were then placed in the incubator. 



Bacteriological control of exjyeriments. — The samples were care- 

 fully inspected from day to day for eAddences of bacterial groAvth. 

 As the moist surfaces of the meat samples and the exuded juices fur- 

 nished an excellent medium for the groAvth of contaminating micro- 

 organisms, such growths, when they occured, soon became percepti- 

 ble to the naked eye. Out of a total of 36 samples, 24 shoAved Aisible 

 bacterial growths upon incubation and these were rejected. In the 

 case of these samples it was not necessary to make cultures, as the 

 bacterial growths Avere quite apparent to the naked eye ; in doubtful 

 cases stained preparations Avere made. Nine of the samples showed 

 no visible bacterial contamination after incubation periods ranging 

 from 7 to 100 days, and these Avere subjected to careful bacteriological 

 examinations in order to establisli their sterility. In examining the 

 samples bacteriologically, cultures were first made from the exuded 

 juice and the outer portions of the meat samples. The samples Avere 

 then cut in half with sterile instruments and cultures taken from 

 the inner jjortions. liotli anaerobic and aerobic cultures were made 

 on several kinds of media. The samples which showed no visible 

 bacterial growths were; foinid to be sterile up(Hi biicteriological cxaini- 

 iKition, and these samples were pasised for chemical examination and 

 .study. 



Saniplirif/ of fresh rn/iterial. — The siun])l('s lia\ iiig been taken for 

 incubati(Mi, a <:oMij>osit(' sample of the lean meat was taken for analy- 



