CH. X ] 



301 



After the sections are spread, drain off most of the water, arrange 

 the sections with a needle or scalpel and place the slide in one of the 

 trays (Fig. 212). Allow it to remain over night or preferably longer. 

 The longer the drying in air the more surety do the sections adhere 

 to the glass slide. 



FIG. 241 



FIG. 242 

 An alcohol or small Bunsen 



FIG. 241. Copper wanning plate on legs, 

 lamp is used with this. It is more satisfactory to spread sections by warm- 

 ing the slides on this plate than to heat them directly over the flame. (Cut 

 loaned by the Spencer Lens Co). 



FIG. 242. Spirit lamp. This is of glass and has the sides flattened so 

 that the lamp rests on one of the sides if it is overturned. (Cut loaned by the 

 Bausch & Lomb Optical Co.). 



If one is in haste to take the succeeding steps in the preparation, 

 the slide may be dried by putting it into a drying oven at 38 1040 

 C. for half an hour or more. The slower drying in air is better if 

 one has plenty of time. 



Some tissues are very difficult to get perfectly smooth as just 

 described. If fine wrinkles persist one can sometimes overcome the 

 difficulty by letting the slide cool and then covering with a piece of 

 fine tissue paper slightly moistened ; press down firmly with the ball 

 of the finger on the sections. Then take hold of the edge of the 

 paper and roll it off the sections. Unless one is careful the sections 

 are liable to come away with the paper instead of adhering to the 

 slide. 



As the water dries out the spread sections come in very close 

 contact with the glass and adhere quite firmly to it. The thinner 

 the sections the more tightly do they stick. This makes it possible 

 to perform the rest of the operations on the slide. One has to be 

 careful not to let strong currents strike the sections. 



