50 Animal Microloyy 



6. Pass the slides up through the series of alcohols to 70 per 

 cent., leaving them about half a minute in each alcohol. 



7. Dip each slide for from thirty seconds to five minutes into 

 the acid alcohol until the sections are of a reddish hue, then rinse 

 them in 70 per cent, alkaline alcohol until the blue color is 

 restored. This last alcohol must be kept very slightly alkaline 

 through the occasional addition of a few drops of a 0.1 per cent, 

 solution of bicarbonate of soda (see memorandum 10). The alka- 

 line alcohol may be omitted when other than hematoxylin stains 

 are used as its purpose is merely to restore the blue color of the 

 latter. 



8. Pass the slides through 95 per cent, alcohol (1 minute), 

 absolute alcohol (3 minutes), into carbol-xylol for 5 minutes or 

 until clear. 



9. Carefully drain off all excess of the clearer, wipe the under 

 side of a slide and lay it down flat with the sections uppermost. 

 Put a few drops of thin balsam on the sections near one end. 

 Take up a clean cover-glass and holding it by the edges between 

 the thumb and first finger of one hand, lower it upon the balsam by 

 bringing one end into contact with the slide near the balsam, and 

 supporting the other end by means of a needle held in the free 

 hand. Lower the cover slowly so that as the balsam spreads no 

 air bubbles will be inclosed under the glass. If a slide is tilted 

 a little and allowed to remain in that position small bubbles will 

 frequently work out unaided. They may sometimes be removed 

 by pressing gently above them with the handle of a needle and 

 gradually working them to the edge of the cover-glass. Keep 

 the slide in a horizontal position until the balsam hardens. 



Caution. Do not allow the sections to become dry before 

 adding the balsam and cover. 



10. Attach the permanent label. It should contain at least 

 the following data: the number of the record card; the name 

 of the tissue; the kind of section (plane of section, thickness, 

 etc.), if one of a series the number of the slide in the series 

 and the number of the first and last section on the slide; the 

 date, and if desired the name or the initials of the preparator. 



