280 



TECHNIQUE 



paraffin enough so that the surface tension of the water will pull 

 the sections out flat. Sometimes sections are badly folded, and in 

 that case one can carefully pull them out flat when the slides are on 

 the warming table. However, such sections are never as satisfac- 

 tory as those which are comparatively flat when received from the 

 microtome. The slides can be left on the warming table until all 

 the water has evaporated or the excess water carefully- removed 

 after the tissue is expanded. Care should be taken that no air 

 bubbles are left under the sections, since the sections are free from 

 the glass at such points and may later fall ofi' the slides or make 



Fig. 166.— Illustration of a warming tabic. (Courtesy of E. Lcitz & Co.) 



une^'en places in the stained and mounted sections. The heat 

 used in flattening the section should not be great enough to liquefy 

 the paraffin of the ribbon pieces. 



A second scheme for fastening sections to slides is to make a 

 solution of 1 ]jart of egg-albumen fixative to 100 parts of cool boiled 

 water. This thin adhesive is added directly to a clean slide, with 

 a pipette, and the ribbon pieces floated on it; the remainder of the 

 process is similar to the foregoing. A third method is to fill a large 

 shallow vessel with water which has been warmed to about 45° C. 

 Small pieces of ribbon are floated on the water. It will be noted 

 that they flatten out immediately. Then a clean slide smeared 

 with egg-albumen fixative can be lowered under such a ribbon 

 piece to remove it. After draining away the excess water and 

 arranging the section, the slide can be set aside until all the water 



