PIPETTES. 



459- 



long. The same pipette can be utilized for preparing a 

 number of such sealed tubes. 



In testing the action of moist lieat on bacteria it is advisable to 

 draw up the liquid into the capillary to a height of 8-10 cm. (3-4 in.)- 

 as shown in Fig. 62 c. The capillary in then sealed at the end and at 

 X just above the liquid. The used pipette can then be drawn out 

 again as in Pig. 62 a. By cutting off the tube above the bulb portion, 

 the capillary portion can be filled and sealed in the manner just 

 described. The same pipette can thus be used for the preparation of 

 a large number of sealed capillary tubes. When it is desired to re- 

 move the liquid from the narrow, sealed, capillary tube, one end should 

 be cut off and sterilized by flaming. This end is then introduced into 

 the culture tube which is to be inoculated, while the sealed end is 

 gradually brought into a Same. The vapor thus produced will drive 

 out the bacterial liquid. 



Fig. (a. Sealing of cultures in capillaries, a— Pipette c Fig. 6i drawn out. When 



filled with liquid it is sealed at x. b — The method of removing the contents from a capillar 



bulb tube. A piece of rubber tubing A;-siips over the end of the large sterile tube; 

 ing and sealing a capillary for thermal death-point determination. 



<;-Fill 



I 



The removal of the liquid from the bulb tube can be accom- 

 plished in the manner indicated; or, by means of the arrangement 

 shown in Fig. 62 6. One end of the narrow tube is opened and steril- 

 ized by flaming. The other end is then opened and inserted into a 

 sterile glass-tube, the end of which is provided with a short piece of 

 rubber tubing. By gently blowing into the tube the contents of the 

 capillary can be expelled into a test-tube or other receiver. 



The ordinary chemical, graduated pipettes ' *are fre- 

 quently made use of. The short 18 cm., 1 c.c. pipettes, as 

 Used in water analysis, are sterilized in a sheet-iron box 



1 A set of three pipettes of excellent construction, with a capa- 

 pacity of ^, ri^ a-nd t^ c.c. respectively, can be obtained of Ruelle, 

 Paris, 6 Rue Chouih. 



