FILLING THE TUBES 147 



and by pressing the pinchcock with which the funnel is 

 provided the desired amount of material (5-10 c.c.) may 

 be allowed to flow into the tubes held under its opening. 

 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. 



FIG. 22 



Funnel for filling tubes with culture media. 



Care should be taken that none of the medium is dropped 

 upon the mouth of the test-tube, otherwise the cotton plug 

 becomes adherent to it, and is not only difficult to remove, 

 but presents a very untidy appearance and interferes mate- 

 rially with the manipulations. 



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

 ized either in the steam sterilizer at 100 C. for fifteen 



