IO8 MANUAL OF BACTERIOLOGY. 



CHAPTER VII. 



COLLECTION OF MATERIAL. 



SAMPLES of water or milk collected in sterilized tubes or 

 bottles, when they are not examined immediately, or when 

 they are to be transmitted any distance, should be kept on 

 ice. Specimens of sputum may be collected in clean bot- 

 tles tightly corked. They should be examined as soon as 

 possible. Although decomposition appears not to interfere 

 with the staining properties of the tubercle bacilli, the spu- 

 tum should be fresh in order that the other bacteria con- 

 tained in it may be studied. Therefore it should be free 

 from contamination with putrefactive germs. Valuable 

 information can also be obtained by examination of spu- 

 tum in a fresh condition before staining (see also page 44). 



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 

 matter in conical vessels is facilitated, although that pur- 

 pose can be accomplished at once by the centrifuge. 

 Thymol will also be a useful addition, as far as a bacterio- 

 logical examination is concerned, in case samples of urine 

 are to be sent by mail; thymol should not be added if cul- 

 tures 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 through the flame three 

 times. Smears of blood are prepared as follows : Have 

 two perfectly clean, square cover-glasses. The finger, or 

 the lobe of the ear, having been carefully washed with 



