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CLINICAL BACTERIOLOGY AND HEMATOLOGY 



It is necessary to lay great emphasis on the fact that the cover- 

 glasses must not be squeezed together, but must simply come 

 together by capillary attraction. 



When the drop has ceased to spread take hold of the upper 

 cover-glass with the finger and thumb of your right hand and 

 slide the two apart, keeping them in the same plane; this is 



Fig. 50. 



readily done, since the cover- glasses are free to turn, being only 

 held loosely at the points. If you do not do this, either the cover- 

 glasses will break, or else the upper cover-glass be lifted from the 

 lower one, and the film will resemble the marks left on a knife which 

 has been pressed on butter and lifted off ; such films are useless. 

 Here, again, you find whether you have taken the right amount 



Fig. 51. 



of blood. If you have taken too little, the cover-glasses will be 

 very difficult to separate ; it may, indeed, be impossible to do so 

 without breaking them. If you have taken too much, they will 

 separate with great readiness, and the blood will spread in uneven 

 smears instead of forming a uniform film. 



I used formerly to recommend the use of forceps for holding 

 the cover-glasses in making these films. The only advantage is 

 that it avoids " steaming " the cover-glasses by the condensation 



