118 LABORATORY EXERCISES IN BACTERIOLOGY. 



interior of the bulb is forced out by holding it close to a flame, and as soon as this 

 is done the capillary end of the tube is plunged into the liquid, the latter being then 

 forced into the interior by external air pressure. After the liquid has entered the bulb 

 the capillary end may be sealed and the bulb and its contents carried to the laboratory 

 for use in inoculation. (If the capillary end was sealed before the collection of the 

 liquid it should have been broken off with a sterile pair of forceps, preferably beneath 

 the surface of the liquid. If the contents of a blister were to have been collected, 

 the surface of the lesion should first have been sterilized surgically and a puncture 

 made with a sterile blade through which the capillary tube is inserted to the interior 

 of the sac.) In the laboratory a tube of medium is placed in a water-bath for lique- 

 faction, and the capillary tube of the Sternberg bulb disinfected and rinsed in boiled 

 water. The plug is withdrawn from the culture tube in the usual manner, and the 

 capillary of the bulb inserted, the sealed end having been broken off with a sterile 

 forceps. The close application of the palm of the hand to the bulb will generally 

 give sufficient warmth to force the contents into the culture tube drop by drop; or a 

 flame may be brought close for the same purpose. After one or more drops have been 

 transferred, the bulb is disposed of, the tube closed in the usual fashion, the infectious 

 material diffused through the medium by agitation, and the tube set aside for whatever 



purpose desired. If there be no further need of the 

 bulb and its contents, it should be placed in a disin- 

 fecting solution and subsequently destroyed in the fur- 

 nace. 



Knife-blades. In the course of autopsies or sur- 

 FIG. 38. STERNBERG BULB. gical operations scrapings from the tissues in suspected 



foci may be transferred to the nutrient media by 



means of long, slender, sterile knife-blades. Thus, if an enlarged gland is to be sub- 

 mitted to a culture examination, such a blade (sterilized in the autoclave or by 

 boiling or disinfectant solution or, if not valuable, by flaming) is driven with its 

 cutting edge well into the tissue, turned on edge, and withdrawn so that the edge 

 will scrape some of the pulp off the cut surface. A tube of medium is taken up and 

 opened as usual, the blade inserted, and some of the adherent pulp smeared well 

 into the surface of the medium if solid, or the blade waved gently in the medium 

 if the latter be liquid, so as to dislodge into it some of the pulp. The blade is then 

 withdrawn and if of no further service is placed in a dish of disinfectant solution. 

 The lip of the tube is flamed, the stopper flamed and adjusted, and the tube, properly 

 marked, is set aside for development of the inoculated bacteria. 



Forceps. Long, slender, sterilized forceps are sometimes used for the convec- 

 tion of infected solid substances to the culture medium. 



Particles. Under various circumstances small bits of solid substances which 

 have been in contact with the infectious matter may advantageously be themselves 

 transferred, with the microorganisms adhering to them, to the nutrient material. 

 For example, when the upper end of the culture tube has been drawn shut in the 

 flame, as is occasionally done instead of closing with a cotton plug, it is a matter of 

 some difficulty to arrange for the entrance of the platinum needle. In such a case it 

 is possible to take up a bit of platinum wire in a forceps and sterilize it well in the flame, 

 dip it into the infected substance, and then drop it into the tube through a small open- 

 ing made by breaking off the tip of the sealed end. The opening thus made is then 

 again sealed in the flame and the tube agitated so as to diffuse the bacteria on the 

 wire through the liquid medium, or over the surface if the medium be solid. Some- 



