TECHNIC 



197 



9. After drying in the air, the slides must be fixed and stained. 



(a) For Ordinary Bacteria. 1. Fix by covering the slide with a sat- 

 urated aqueous solution of mercuric chlorid for one minute. Wash in 

 water. 



2. Cover with carbolthionin and stain for one or two minutes. 

 "Wash in water. 



FIG. 49. MIXING THE CONTENTS OF A CAPILLARY PIPET. 

 Due precautions must be exercised to avoid the formation of bubbles. 



3. Dry thoroughly. 



(b) For Acid-fast Bacilli. 1. Fix by inverting the films for thirty 

 seconds over a watch-crystal or jar containing formalin, being careful 

 that there are no drops of formalin on the edge of the vessel that might 

 come in contact with the preparation. The films may be fixed also 



