70 MICROSCOPICAL EXAMINATION OF BACTERIA 



4. A square glazed earthenware box with a loose 

 lining containing 2 per cent, lysol solution for the 

 reception of infected material and used slides. The 

 bottom of the lining is perforated so that when full the 

 lining and its contents can be lifted bodily out of the 

 box, when the disinfectant solution drains away and the 

 slides, etc., can easily be emptied out. The empty lin- 

 ing is then returned to the box with its disinfectant 

 solution (Fig. 61). 



5. Bunsen burner provided with "peep-flame" 

 by-pass. 



6. Porcelain trough holding five or six hanging-drop 

 slides (Fig. 62). 



FIG. 62. Hanging-drop slides: a, Double cell seen from above; b single 

 cell seen from the side. 



The best form of hanging-drop slide is a modification 

 of Boettcher's glass ring slide, and is prepared by 

 cementing a circular cell of tin, 13 to 15 mm. diameter, 

 and i to 2 mm. in height, to the centre of a 3 by i slip 

 by means of Canada balsam. It is often extremely 

 convenient to have two of these cells cemented close 

 together on one slide (Fig. 62, a). 



Another form of hanging-drop slide is made in which a circular 

 or oval concavity or "cell" is ground out of the centre of a 3 by i 

 slip. These are more expensive, less convenient to work with, 

 and are more easily contaminated by drops of material under 

 examination, and should be carefully avoided. 



