138 GENERAL BACTERIOLOGICAL DIAGNOSIS 



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 is allowed to flow away (as it might 

 be spoilt by containing some of the anti- 

 septics 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 quarter-filled with water and 

 vigorously 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 absorbent 

 wool, which is then placed in a sterile vessel. 

 Wool or gauze used for this purpose, or for 

 swabbing, say the throat, to obtain shreds of 

 suspicious matter, must have no antiseptic 

 FIG. 46. Test-tube impregnated in it, as the latter may kill the 

 ^o-^ffr.t n Kffn bacteria present and make the obtaining of 



rciiigCQ. lor o ijitiiii- . . 



ing fluids contain- cultures impossible. 



ing bacteria. Fluids from the body cavities, urine, etc., 



may be secured with sterile pipettes. To make 

 one of these, take 9 inches of ordinary quill glass-tubing, draw 

 out one end to a capillary diameter, and place a little plug of 

 cotton wool in the other end. 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. 46). Another method 

 very convenient for transport is to make two constrictions on 

 the glass tube at suitable distances, according to the amount of 

 fluid to be taken. The fluid is drawn up into the part between 

 the constrictions, but so as not to fill it completely. The tube 



