FATE OF TUBERCLE BACILLI OUTSIDE THE ANIMAL BODY 

 TABLE 8. ORGANISMS EXPOSED TO DIRKCT SUNLIGHT 



315 



1 Time of exposure was not continued longer; no end point was reached. 



EFFECT OF DIRECT SUNLIGHT UPON TUBERCLE BACILLI 



CULTURE AND x 11V - tiA ^t of direct sunlight was tested several 

 EMULSION times upon cultures from three types of tubercle 



bacilli. The organisms used for exposure were 

 always from active cultures grown upon glycerine egg from two to 

 three weeks. A heavy emulsion was made by rubbing up some of 

 the 'culture on the inside of the neck of a sterile glass-stoppered 

 graduate fiask with a sterile glass rod. From time to time a few 

 drops of sterile 0.8 percent salt solution were added. At first 

 the culture was rubbed into a fine paste with the addition of only 

 a few drops of the salt solution; then about 6 cc. of 0.8 percent 

 salt solution were added and, the contents shaken thoroly. The 

 emulsion then showed a decidedly milky appearance and was 

 filtered thru sterile glass wool to remove the larger clumps. The 

 examination of a stained preparation, made in a similar way as 

 the smears that were used for exposure to sunlight,, showed the in- 

 dividual organisms usually well separated. There were, however, 

 clumps of twenty-five to thirty organisms still to be found. 



PREPARATION Smears from the prepared emulsions were made 

 upon small slips of sterile glazed paper. Pins 

 pushed thru the corners of these small paper slips 

 were then stuck into the bottom of a pasteboard box having a snug 

 fitting lid. The box and the slips were sterilized at 150 C. for 

 one hour. A small loopful of the emulsion was smeared in a thin 

 layer upon each of the sterile glazed paper slips. These were ex- 

 posed at once to the sun for the desired length of time. Triplicate 

 smeared slips for cadi period of exposure were seeded upon culture 

 media suitable for the growth of tubercle bacilli. The media used 

 was 5 percent glycerine beef -juice agar or glycerine egg. 



