and Laboratory Methods. 



1803 



which terminates in a capillary tube 8 cm. in 

 length. The bulb (b) constitutes the reservoir 

 for the inoculating material. 



Method. — Pour about 20 c. c. of medium 

 into the flask by means of a drawnout pipette. 

 Then taper the neck still more so that it can 

 be sealed easily and quickly. After cooling 

 dip the lateral tube into the inoculating ma- 

 terial and by means of suction at (S) draw the 

 latter up until it reaches (a). Seal the outer 

 end of the lateral tube in the flame until a 

 powerful stream of vapor evolves from the 

 ^^^- ^^- narrow opening of the neck. After the steam 



has escaped for about four minutes seal the tapering neck in the flame. When 

 the medium is cooled down to 40°C., slightly warm the inoculating material in 

 the reservoir of the lateral tube. By this means it is forced into the flask, where 

 it should be well distributed all through the medium by slightly shaking the 

 flask. Now melt off the lateral tube at (a) and place the flask in the incubator. 

 VignaPs Method. Taper an open glass tube (Fig. 41) at one end and plug 

 it with absorbent cotton at the other. When sterilized dip the tapered end of 

 the sterile tube into the inoculated medium (liquified agar or gelatin) and fill the 

 tube by suction at (a) ; when filled seal both ends in the flame. In order to 

 make subcultures from the isolated colonies developed in this tube, cut the tube 

 in two. 



Roux's pipette cultures : (Fig. 42). The pipette consists of a glass tube 

 drawn into a capillary tube at its lower end and constricted 

 at (r). 



Method. — Seal the capillary end (B) in the flame, insert 

 a loose cotton plug at end (A) and sterilize the apparatus 

 at 150°C. Break off the seal at (B) and dip the 

 '*^ capillary tube into sterile, liquified nutrient agar or 

 gelatin which has been boiled immediately before. 

 When the tube is filled up to constriction (r), press 

 the finger tightly over the upper opening (A) and 

 quickly raise the tube into an oblique position. 

 This will prevent the medium from running out. 

 Now seal at (B) and then at (r) in the flame. For 

 inoculation open one end, make a thrust with a fine, 

 infected glass needle, and seal again. 



Nikiforoff (1890) constructed the capillary tube 

 shown in Fig. 43. The apparatus consists of a 

 reservoir (a), which is constricted and sealed at one 

 end (b) and drawn out into a capillary tube about 

 25 cm. long at the other end (c). The capillary 

 tube is U-shape. Heat the reservoir (a) of the 

 Fig. 41. sterile capillary tube, then dip its open end (c) into 



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