Journal of Applied Microscopy. 



103 



sold by Gruebler (Leipzig, Germany), 

 known as "eosin blaeulich" (of bluish 

 color), soluble in water. Of this a one 

 per cent, solution is maae in distilled 

 water, that is, one gram to one hundred 

 cubic centimeters of the water. 



Picric acid — acid fuschin solution (Van 

 Gieson's Stain). 



1% acid fuchsin solution in distilled 

 water, 5 to 7 ccm. 



Saturated aqueous solution of picric 

 acid 100 ccm. 



STAINING OF. SECTIONS WITH THE SOLUTIONS 

 DESCRIBED. 



Paraffin Sections. — In order to stain 

 paraffin sections readily, it is desirable 

 to remove the paraffin from the sections 

 before staining. Before doing this, how- 

 ever, it is well to fix the sections to 

 slides or cover-glasses, preferably the 

 latter, otherwise the sections become 

 somewhat difficult to handle; they are 

 apt to tear, or some of the cells or nests 

 of cells, loosely adherent to the surround- 

 ing tissue, are likely to be lost in tha 

 manipulations. 



The process followed in this laboratory 

 for fixing sections to a cover-glass is as 

 follows (cover-glasses are as a rule used 

 because they are more easily mani- 

 pulated, require less of the solutions, 

 etc.) : i t is essential that the cover- 

 glasses be perfectly clean before they 

 are used for this purpose. They may be 

 cleaned by placing them for a feAV 

 moments in sulphuric acid, nnsing off the 

 acid and pouring on strong acetic acid, 

 and after shaking the dish or beaker a 

 little while, the acetic acid is poured off, 

 and the cover-glasses are thoroughly 

 washed in flowing water, if that is at 

 hand, or by frequently changing the 

 water on the cover-glasses. After 

 thorough washing they are placed in 

 alcohol, and the alcohol wip^d from them 

 with a clean, soft linen cloth. A large 

 number of cover-glasses may be cleaned 

 in this way at one time and kept in "pill- 

 boxes," ready for future use. 



As paraffin sections are usually some- 

 what folded or wrinkled when taken 

 from the knife, especially if large, the 

 following routine method has been fol- 

 lowed in this laboratory for flattening 

 out paraffin sections. A small evaporating 

 dish, 4 or 5 inches in diameter, is nearly 

 filled with distilled water. This is placed 

 on a support, high enough so that a Bun- 

 sen burner or an alcohol lamp may be 

 placed under the dish. One or two of the 

 paraffin sections are then floated on the 

 distilled water. The water is them care- 

 fully heated until the sections and the 

 paraffin surrounding the sections become 

 perfectly flat. Care should be taken not 

 to heat the water sufficiently to cause 

 the paraffin to melt. As soon as the sec- 



tions are flat, the flame should be 

 removed. Other sections may now be 

 placed on the warmed water, and as 

 soon as flat may be taken up on a cover- 

 glass which has been coated by a very 

 thin layer of "albumen fixative." 



Albumen fixative is a mixture of equal 

 parts of the white of egg and glycerine, 

 and is prepared by chopping up the white 

 of one or two eggs in a beaker with scis- 

 sors and stirring in an equal quantity ^•f 

 pure glycerine. The mixture should then 

 be filtered through fine linen into a clean 

 bottle. The bottle should be provided 

 with a cork through whicn a small glass 

 rod has been pushed. A very small drop 

 of this fixative is placed on each cover- 

 glass to be used, and spread with the 

 finger into a very thin layer. A cover- 

 glass 6oated with albumen fixative is 

 now taken up with a pair of cover-glass 

 forceps and slipped, albumen fixative 

 side up, under one of the sections floating 

 on the warmed water, and while with- 

 drawing the cover-glass, the section is 

 drawn on to it with a needle or small 

 camel's hair brush. The excess of water 

 is now drained from the cover-glass by 

 holding its edge to a filter paper. A lit- 

 tle practice enables one to fix to cover- 

 glasses, after this method, twenty or 

 thirty sections in a very few minutes. 

 The cover-glasses to which sections have 

 been fixed are now set aside until all the 

 water has had time to evaporate. Five 

 to eight hours are sufficient, depending 

 somewhat on the temperature and the 

 dryness of the room. This step may be 

 hastened somewhat if the cover-glass 

 preparations can be placed in a warm 

 oven, the temperature of which should 

 not, however, exceed 40° C. When the 

 sections fixed to the cover-glasses are 

 perfectly dry, the paraffin is removed as 

 follows: 



A cover-glass to which a section is 

 fixed is grasped in the cover-glass for- 

 ceps and held over the flame until the 

 paraffin in and around the section is 

 melted, care being taken not to overheat 

 the preparation. The cover-glass is now 

 placed in xylol, where it remains until the 

 paraffin is dissolved out of the section 

 fixed to it. This usually takes only two 

 or three minutes. The xylol is now 

 drained off by holding the edge of the 

 cover-glass to filter paper, and the cover- 

 glass is transferred to absolute alcohol, 

 this to remove the xylol from the section. 

 It is next transferred to 95% alcohol and 

 then to distilled water, allowing to each 

 step two or three minutes. 



It is convenient to arrange the dishes 

 required to hold the fluids for the pre- 

 ceding and succeeding steps in one or 

 two rows on a sheet of filter paper. The 

 cover-glasses can then be transferred 

 from one to the other with little incon- 



