462 



BACTERIOLOGY. 



is then removed from the upper end of the aerobioscope, 

 and the desired amount of air is aspirated through the 

 sugar. Dust particles and bacteria will be held back 

 by the sugar. During manipulation the cotton plug is 

 to be protected from contamination. 



FIG. 97. 



Bent funnel for use with aerobioscope. 



When the required amount of air has been aspirated 

 through the sugar the cotton plug is replaced, and by 

 gently tapping the aerobioscope while held in an almost 

 horizontal position, the sugar, and with it the bacteria, 

 are brought into the large part (e) of the apparatus. 

 When all the sugar is thus shaken down into this part 

 of the apparatus, about 20 c.c. of liquefied, sterilized 

 gelatin is poured in through the opening at the end c, 

 the sugar dissolves, and the whole is then rolled on ice, 

 just as is done in the preparation of an ordinary 

 Esmarch tube. 



The gelatin is most easily poured into the aerobio- 



