XX 



in the dark. Wash thoroughly in water till colourless. 

 Transfer to alcohol, seventy to eighty per cent., for preservation. 



Flemming's Solution. — Chromic acid, i per cent., 15 vols. 

 Osmic acid, 2 per cent., 4 vols. 

 Glacial acetic acid i vol. 



Mix in the above proportions before use. Use. very small 

 pieces. Fixation is complete, in about tvi^enty-four hours. 

 Blackening due to the osmic may be removed by hydrogen 

 peroxide. Blood films may be fixed in this solution. 



Tissues thus fixed may be preserved in equal parts of 

 alcohol and glycerine. 



Formalin (forty per cent, solution of formaldehyde). — Use 

 two to five per cent, solution in water. Small pieces are fixed 

 in twelve to twenty-four hours. They may be left in solution 

 or transferred to alcohol. 



Corrosive Sublimate. — Best used as a concentrated alcoholic 

 solution (or aqueous may be used). Fixation takes place in a 

 few hours. Wash thoroughly in water and transfer to iodine 

 solution {vide Zenker's fluid) till iodine no longer decolourized. 



The concentrated alcoholic solution is a most rapid fixing 

 and hardening reagent, and sections can be cut in a very short 

 time, if small pieces are used. 



Decalcifying Solution. — Tissues require fixing before and 

 after these solutions — 



(i) Phloroglucin, one gramme, nitric acid, ten c.c, water, 

 one hundred c.c. ; or 



(ii) One to five per cent, solution of nitric acid in water 

 or alcohol. Change the fluid daily. Decalcification takes 

 place in two to three days. 



(iii) Picric acid, a saturated solution (= about 075 per 

 cent.) containing crystals. Decalcification may take weeks or 

 months. Wash in alcohol. 



Eau de Javelle (dissociating and decolourizing solution). — 

 Add to a concentrated aqueous solution of chloride of lime a 

 solution of potassium oxalate as long as a precipitate is 

 formed. Filter and dilute if necessary. This may be used for 

 softening the chitinous skeleton of mosquitoes afid for decolour- 

 izing Madura fungus, etc. 



For Fixing Paraffin Sections to the Slide 



1. Celloidin, one part, oil of cloves, two parts ; or 



2. Thin solution of white shellac in creosote ; or 



