CULTIVATION IN LIQUID MEDIA 



93 



3. Tilt the pipette so as to raise the point and seal the latter in a small 

 flame. 



4. Connect the other end to an exhaust pump. Exhaust and wash with 

 hydrogen alternately. 



It is often sufficient when a vacuum is established to boil the liquid as described at 

 p. 91. When the pipette is heated even very slightly the liquid will boil violently and 

 will tend to pass into the aspirating tube ; this may be prevented by first heating the 

 upper part of the tube above the liquid. 



5. Seal the pipette at the constriction a, in vacuo. Dip the ends of the 

 pipette into Golaz's wax to strengthen them. Incubate. 



6. When the culture has grown, flame and break the end a of the pipette 

 and withdraw the culture by means of a Pasteur pipette. 



C. Pasteur, Joubert and Chamberland's tube. With this apparatus two 

 successive cultures can be sown without exposing the medium to the air 

 while sowing the second culture. 



It consists (fig. 80) of an inverted U-tube, each limb of which is provided with a 

 lateral tubulure terminating in a fine point. A third tubulure originates from the 

 convexity of the U, and this is constricted in two places a short distance apart, 

 and plugged with wool between the two constrictions. 



FIG. 80. Pasteur, Jou- 

 bert and Chamberland's tube 

 for the cultivation of anae- 

 robic organisms. 



FIG. 81. Pasteur's tube 

 for the cultivation of anae- 

 robic organisms. 



FIG. 82.-.-Lacpmme'stube 

 for the cultivation of anae- 

 robic organisms. 



1. Plug the vertical part C with wool between the constrictions c and c ]? seal the points 

 of the lateral tubulures a and b and sterilize the tube in the hot air sterilizer. 



2. When it has cooled, flame the lateral tube a, break off its point and dip the latter 

 into the broth, which has been sown beforehand. Aspirate the liquid into the limb A 

 by applying suction to C. Seal up the end of a in the flame again. 



3. Flame the lateral tube 6, break off its point, dip the end into a tube of sterile broth, 

 and aspirate the broth into the limb B. Seal the end of b in the flame. 



Note. In carrying out the second and third operations, be careful that the liquids 

 in the two limbs do not mix. The limbs should not be more than one-third filled. 



4. Attach the upper end of C to the exhaust pump. Exhaust the air, and wash two 

 or three times with hydrogen. Seal the tube at the constriction c in vacuo. 



5. Incubate the tube in the vertical position. Growth will occur in A, while the broth 

 in B will remain clear and serve as a control. 



6. When growth in A has ceased, tilt the apparatus so that a drop or two of the culture 

 passes from A into the sterile broth contained in B. Incubate again, and growth will 

 now take place in B. 



D. Pasteur's tube. This is a more simple form of the preceding, and 

 consists of a single limb of the U-tube just described (fig. 81). 



After sterilizing the tube aspirate the broth, already sown with the organism, through 

 the narrow tube a, seal the point of a in the flame, exhaust through B, seal this tube 

 at b and incubate. 



Lacomme's tube (fig. 82) is a modification of Pasteur's; it is used in an exactly similar 

 manner, and is cheaper. 



