and Laboratory Methods. 2009 



2. Alcohol, Ether, and Sublimate. — Gulland (1887) recommends the following 

 mixture for fixing undried blood films : 



Absolute alcohol saturated with eosin, - 25 c. c. 

 Pure ether, - - - - - - - 25 c. c. 



Sublimate in absolute alcohol (2 g. to 10 c. c.) 5 drops 



The fresh preparations are dropped wet side downward into the fixing solu- 

 tion. The fixation is practically instantaneous, but the preparations should 

 remain in the solution at least three or four minutes to fix the film to the cover. 

 The preparations are stained by the eosin in the fixing solution and may be 

 counterstained with methylen blue. 



3. Chromic Acid. — Harris (1883) used chromic acid (i per cent.) and also 

 potassic bichromate (^ to ^ per cent.) ; preparations to remain in the fixative 

 several days, then wash twelve to twenty-four hours in running water. 



4. Flemming's Solution — Cornil (1S87) fixed fresh blood films in Flemming's 

 solution for several hours. 



Miiir (1891) dropped the fresh blood into strong Flemming's solution, em- 

 bedded the drop in paraffin and sectioned. " This method shows the structure 

 of the leucocytes well, but the character of the red corpuscles is poorly shown, 

 and in ordinary conditions but few leucocytes are seen in one section." 



Deetjen (1901) used Flemming's solution for fixing blood plates in fresh 

 blood spread on an agar solution instead of glass (see IV, 9). The fixative was 

 allowed to flow under the cover-glass for from three to five minutes. 



5. Formalin. — Heiman (1898) recommends formalin, — 



Formalin (40 per cent.) - - - 10 c. c. 

 Water, - - - - - - - 30 c. c. 



Fresh, undried blood films are exposed to the vapor of this solution contained 

 in a wide mouth bottle for from five to ten minutes. The solution will remain 

 good about two months. 



Kizer (1900) gives the following method of fixing blood with formalin : 

 " Mix one volume of perfectly fresh blood with three volumes of a two per cent, 

 solution of formalin. Allow the mixture to stand at least an hour ; then draw a 

 small quantity from the bottom of the vessel with a pipette, by which a drop is 

 transferred to a clean coverslip, and allow the liquid to evaporate. The 

 method of pressing the coverslips together, as in sputum analysis', is to be pre- 

 ferred. Pass the coverslip through the flame, film uppermost, in order to cement 

 the corpuscles to the glass. Dip into a five per cent, solution of acetic acid once 

 or twice, and remove the acid with water." 



6. Hermann's Fluid. — Miiller (1892) used Hermann's fluid (1 per cent, plat- 

 inic chloride 15, 2 per cent, osmic acid 4, acetic acid 1). The preparations, 

 either absolutely fresh or more or less dried, were brought into the fluid and 

 allowed to remain several days to a month (Miiller recommends ten days). 

 Wash in running water twelve to twenty-four hours. 



7. Mercuric Chloride. — Freeborn (1889) put a drop of mercuric chloride in 

 the form of Pacini's or Hayem's solution on the finger and pricked the latter 

 through the fixative. The drop of fluid and the drop of blood were mixed with 

 the needle, and then transferred to a slide and covered. 



