116 GENERAL BACTERIOLOGICAL DIAGNOSIS 



being contaminated with extraneous organisms ; (2) that nothing 

 be done which may kill any organisms which may be proper to 

 the inquiry ; and (3) that the bacteriologist obtain the material 

 as soon as possible after it has been removed from its "natural 

 surroundings. 



The sources of materials to be examined, even in patho- 

 logical bacteriology alone, are of course so varied that we can 

 but mention a few examples. It is, for instance, often necessary 

 to examine the contents of an abscess. Here the skin must be 

 carefully purified by the usual surgical methods ; the knife used 

 for the incision is preferably to be sterilised by boiling, the first 

 part of the pus which escapes allowed to flow away (as it might 

 be spoiled by containing some of the antiseptics used in the 

 purification) and a little of what subsequently escapes allowed 

 to flow into a sterile test-tube. If test-tubes 

 sterilised in a laboratory are not at hand, an 

 ordinary test-tube may be a quarter filled with 

 water, which is then well boiled over a spirit- 

 lamp. The tube is then emptied and plugged 

 with a plug of cotton wool, the outside of which 

 has been singed in a flame. Small stoppered 

 bottles may be sterilised and used in the same 

 way. A discharge to be examined may be so 

 small in quantity as to make the procedure 

 described impracticable. It may be caught on 

 a piece of sterile plain gauze, or of plain ab- 

 sorbent wool, which is then placed in a sterile 

 vessel. Wool or gauze used for this purpose, 

 or for swobbing out, say the throat, to obtain 

 shreds 'of suspicious matter, must have no 

 antiseptic impregnated in it, as the latter may 

 kill the bacteria present and make the obtaining 

 of cultures impossible. 



Fluids from the body cavities, urine, etc., 

 may ^ e sec ured with sterile pipettes. To make 



T of * ese > ' ake nine inches / ordinary quill 

 glass-tubing, draw out one end to a capillary 

 diameter, and place a little plug of cotton wool 

 Insert this tube through the cotton plug of an 

 ordinary test-tube and sterilise by heat. To use it, remove 

 test-tube plug with the quill tube in its centre, suck up some 

 of the fluid into the latter, and replace in its former position 

 in the test-tube (Fig. 48). Another method very convenient for 

 transport is to' make two constrictions on the glass tube at 



FIG. 48. Test-tube 

 and pipette ar- 



ing bacteria. 

 in the other end. 



