METHODS OF EXAMINATION. 



29 



slide, with a drop of sterilized water, or bouillon, and from this 

 a little is taken on cover-glass, as before. 



The cover-glass with its drop is now placed on the glass slide, 

 carefully pressing out all bubbles. Then a drop of cedar-oil is 

 laid on top of the cover-glass, and the oil immersion lens dipped 

 gently down into it as close as possible to the cover-glass, 

 the narrow blender shutting off the Abbe condenser, for this 

 being an unstained specimen, we want but little light. We 

 now apply the eye, and if not in focus, use the fine adjust- 

 ment or the coarse, but always away from the object i. e. towards 

 us since the distance between the specimen and the lens 

 is very slight, it does not require much turning to break the 

 cover-glass and ruin the specimen. Having found the bacte- 

 rium, we see whether it be bacillus, micrococcus, or spirillum ; 

 discover if it be motile, or not. That is about all we can ascer- 

 tain by this method. 



FIG. 10. 



Hanging Drop in Concave Glass Slide. 



Hanging Drop. When the looped platinum needle is dipped 

 into a liquid, a very finely-formed globule will hang to it ; this 

 can be brought into a little cupped glass slide (an ordinary 

 microscopic glass slide with a circular depression in the centre) 

 in the following manner : The drop is first brought upon a 

 cover-glass ; the edges of the concavity on the glass slide are 

 smeared with vaseline, and the slide inverted over the drop ; 

 the cover-glass sticks to the smeared slide, which, when turned 



