THE HANGING-DROP. 141 



structive distillation; the cover-glasses are, as a result, per- 

 fectly clean, and they remain thus, as long as they are kept 

 in the covered dish. It is advisable to clean up a box of 

 cover-glasses at a time. The Fresenius iron drying plate, 

 with its six cups, is especially convenient for student's use. 

 The temperature of this plate can easily be raised to 200^ 

 Only very rarely, will this procedure for obtaining clean 

 cover-glasses, fail. In such cases, an additional passage 

 of the cover-glass, two or three times, through the flame, 

 will give a suitable surface. The droplet of water, or the 

 bacterial suspension, should be placed on that side of the 

 cover-glass which touched the flame. 



The cover-glass should always be handled with a pair 

 of forceps. The ordinary, slender, narrow-pointed forceps, 

 are well adapted for this purpose. In staining, however, 

 they have one serious disadvantage. The weak blades 

 compress on the slightest pressure, and form a capillary 

 along which the staining reagent readily drains from the 

 cover-glass. Under these conditions, the hands of the stu- 

 dent stain more readily than does the specimen. 



FIG. 20. Cover-glass forceps of the author, a Simple 

 form; b Forceps provided with clasp. 



The forceps devised by the author, and shown in Pig. 20, 

 are extremely convenient in handling cover-glasses. The 

 lower blade is flat and has a broad end (2 mm. wide), with a 

 thin, sharp edge. The upper blade is narrow, bent, and 

 terminates in a point, which, when the forceps are shut, rests 

 close to the end of the lower blade. The advantages pos- 

 sessed by these forceps are, that it enables one to pick up 



