FILLING THE TUBES. 79 



desired amount of material (5-10 c.c.) may be allowed 

 to flow into the tubes held under its opening. 



FIG. 



It is not necessary to sterilize the funnel, for the 

 medium is to be subjected to this process as soon as it is 

 in the test-tubes. 



Care should be given that none of the medium is 

 dropped upon the mouth of the test-tube, otherwise the 

 cotton plugs become adherent to the tube and are not 

 only difficult to remove, but present a very untidy ap- 

 pearance, and interfere, indeed, with the proper manipu- 

 lations. 



As soon as the tubes have been filled they are to be 

 sterilized in the steam sterilizer for fifteen minutes on 



