384 



PREPARATIONS BY THE PARAFFIN METHOD [Cn. XI 



and place the slide in one of the trays (figs. 206-207). Allow it to re- 

 main overnight or preferably longer. The longer the drying in air 

 the more surely do the sections adhere to the glass slide; or use the 

 drying oven (fig. 244). 



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 to 40 C. 

 for half an hour or more. 



Some tissues are very difficult to get perfectly smooth, as just de j 

 scribed. If fine wrinkles persist, one can sometimes overcome the 

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



FIG. 230. Two MICROSCOPES AND A CHALET LAMP ON A LABORATORY TABLE. 



(See also Fig. 125.) 



(About one ninth natural size). 



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. 



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

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

 sections the more tightly do they stick. 



621. Deparaffining in xylene. This is accomplished by using a 

 solvent of paraffin. The best and safest one to use in a laboratory 



