132 



Arranging and fastening sections on the slide.— 



If serial sections are being cut and the series is long and the 

 sections of considerable size, larger slides than the ordinary 

 3 in. by i in. slides can be used to advantage. For most 

 work, however, the smaller slides do very well. The sec- 

 tions are to be arranged in regular order in successive lines 

 either parallel with the short or long axis of the slide as 

 preferred, leaving uncovered only enough room at one end 

 of the slide for a suitable label. The rows of sections should 

 be near together, and the sections near together in each 

 row, i.e., the paraffin block should, before cutting, be 

 trimmed as small as is safe. This economizes slides and 

 covers, and makes the series far more compact and therefore 

 more readily examined. 



Before arranging the sections on the slide, the slide 

 should be very thinly covered (by rubbing with the finger 

 tip) with Mayer's albumen fixative (Lee's Vade-Mecum, p. 

 143), which can be bought of dealers in microscopical sup- 

 plies. Then allow a few drops of distilled water from a 

 pipette to flow over the slide so that the sections msiy Jloat. 

 This will straighten out any folded or crumpled sections. 

 The water must be allowed to evaporate slowly, by putting 

 the slide on top of the paraffin oven or otherwise heating it 

 slightly, being careful not to melt the paraffin. After the 

 sections are entirely dry, the slide should be placed in the 

 paraffin oven, and allowed to remain until the paraffin is 

 melted. Or the slide may be gently and carefully warmed 

 over a gas or alcohol flame. The slide should not be heated 

 to a temperature higher than required to melt the paraffin. 

 After the paraffin is melted the slide should be allowed to 

 cool until the paraffin hardens again. 



Removing the paraffin. — The slide should now be put 

 into a small jar of xylol, which will quickly dissolve the 

 paraffin. Leave it in the xylol for about ten minutes, even 



