46 PRACTICAL HISTOLOGY [VI 



warm the sections will flatten. As soon as the sections are 

 flat, remove the slide, let the water run off, and treat as after 

 the corresponding stage in a. With delicate sections it is better 

 not to remove excess of water with blotting-paper, but after 

 draining, to let the sections dry in the warm bath ; in this case 

 they should be left at 35 C. till next day. The drying period 

 may be shortened thus : after the slide has been at 35 C. for 

 half-an-hour (i) leave it in 95 p.c. alcohol for a few minutes, 

 drain, and put on the bath for another half-an-hour, or (ii) treat 

 similarly with absolute alcohol, drain, put in turpentine at once. 



c. Proceed as in b, but use 50 p.c. spirit instead of water. 



5. /Staining serial sections on the cover-slip or slide, a. The 

 several fluids required (turpentine or xylol, alcohols, staining 

 agents) are arranged in a row in bottles without necks. (If a 

 slide is used, the bottles should just hold the slide.) 



Proceed at first as in 4, either a, 6, or c. If the cover-slip 

 taken was clean and the process has been properly carried out, 

 the sections will in most cases adhere to it during the subse- 

 quent staining and mounting. 



After the paraffin has been dissolved in turpentine or xylol, 

 wipe or drain off excess of fluid and place in absolute alcohol for 

 two or three minutes ; transfer for a minute to 95 p.c. alcohol, 

 and so on through the successive alcohols to the staining agent, 

 e.g. Delafield's hsematoxylin. When the section is stained 

 remove excess of staining fluid, pass back through the alcohols, 

 removing excess of fluids at each transfer. After absolute 

 alcohol, leaye the slide in turpentine or xylol for a couple of 

 minutes ; then stand it up to drain ; mount as in 3. 



Some sections, especially those of tissues which have been 

 kept long in osmic acid or in chromium compounds, are apt to 

 come away from the glass when treated as above. In such cases 

 a fixative is used as in 6, and c, following. 



b. If the sections do not require to be flattened, rub the 

 cover-slip or slide with a mixture of egg-albumin and glycerine 

 (p. 313) in the manner in which collodion was used in 3. 



