260 MICROBES, FERMENTS, AND MOULDS. 



dehydrate and partially decolourize preparations. 

 Canada balsam is used to mount them; and finally 

 distilled water, absolutely free from microbes, which 

 may be easily obtained by means of the Chamberland 

 filter already described, is used for washing instru- 

 ments, etc. 



Mode of collecting the Liquids to be examined. In 

 order to collect the liquids to be obtained 

 in the wards of a hospital or elsewhere 

 (blood, urine, sputum, stagnant or sewer 

 water, etc.), pipettes, which may be either 

 straight or with twisted necks, are used, 

 ending in a capillary point closed by 

 heat, and in its upper part by a stopper 

 of fine, sterilized cotton wool. The 

 pipette is heated at a blowpipe flame, 

 in order to destroy the germs. When it 

 is to be used, the point is broken off, 

 and it is plunged into the liquid (dis- 

 charge from a freshly opened abscess, 

 blister of erysipelas, etc.), and an aspira- 

 tion is made through the other end. The 

 liquid is unable to rise above the level 

 of the twisted neck; and this is important, 

 especially when the aspiration is made 

 by the mouth. The point is then resealed 

 at the lamp. The shape of these pipettes 

 may be varied according to the require- 

 ments, so long as the same precautions are always 

 taken to avoid mistakes. 



Fig. 102. Small 

 pipette with 

 twisted neck, 

 corked with cot- 

 ton wool and 

 sterilized. 



