COLLECTION OF MATERIAL. 97 



CHAPTER VII. 

 COLLECTION OF MATERIAL. 



Samples of water or milk should be examined as soon after 

 drawing as possible; but when this is impossible, as in the case 

 where they are transmitted from a distance, they should be 

 collected in sterilized tubes or bottles, which should be kept on 

 ice. Specimens of sputum should be collected in clean bottles 

 tightly corked. The early morning sputum is to be preferred 

 for examination. The patient should be directed to rinse out 

 the mouth carefully, and cough up material from the lungs, not 

 merely to clear out the throat as is sometimes done. It should 

 be examined as soon as possible. Although decomposition ap- 

 pears not to interfere with the staining properties of the tubercle 

 bacilH, the sputum should be fresh in order that the other 

 bacteria contained in it may be studied. Therefore it should 

 be free from contamination with putrefactive germs. Valuable 

 information can also be obtained by examination of sputum in 

 a fresh condition before staining (see also page 33). 



Samples of urine keep better after the addition of a few 

 crystals of thymol, which retards the fermentative process, so 

 that the sedimentation of the bacteria and of other solid mat- 

 ter in conical vessels is facilitated, although that purpose can be 

 accomplished at once by the centrifuge. Thymol will also be 

 a useful addition, as far as a bacteriological examination is con- 

 cerned, in case samples of urine are to be sent by mail; thymol 

 should not be added if cultures are to be made. 



Specimens of sputum, pus or blood may be collected con- 

 veniently in the form of thin smears upon cover-glasses. The 

 smears are fixed by passing thropgh the flame three times. 



