APPENDIX III 



PETER GRAY'S BASAL SOLUTIONS FOR LABORATOR\ 



FIXATIVES * 



1431. Fixative solutions are often required in small quantities. 

 Their preparation from stable basal solutions (Gray, Journ. R. 

 Microsc. Soc, liii, 1933) prevents waste of time, material 

 and storage space. Ten aqueous and two alcoholic solutions are 

 required :— 



(1) 80% nitric acid. 



(2) 40% formaldehyde. 



(3) Glacial acetic acid. 



(4) 2% chromic acid. 



(5) 7-5% potassium 



mate. 



(6) " Miiller X 3 " (7-5% po- 

 tassium dichromate plus 

 3% sodium sulphate). 



(7) 7% mercuric chloride, 

 dichro- (8) Saturated picric acid. 



(9)1% "platinic chloride" 



(PtNagCle). 

 (10) 2% osmic acid. 



(11) 1% picric acid in 95% alcohol. 



(12) 1% each of picric acid and mercuric chloride in 95% alcohol. 



Notes. Aqueous solutions (1) to (9) and both alcoholic solutions 

 are stable, and of constant content, at temperatures above 12° C. 

 Solutions (5), (6) and (7) start throwing down crystals if dropped 

 below this point. Solution (10) is stable only in chemically and 

 mechanically clean bottles in the presence of from 0-01 to 0-05 

 per cent, potassium permanganate ; this concentration, which 

 is easily judged colorimetrically, must be maintained by periodic 

 additions of a stronger solution. Such osmic solutions have 

 retained their strength for three years. {P.O.) 



Solution (5) may be substituted for solution (6) by those who 

 do not believe in the efficacy of the sulphate content of Miiller. 

 Gray {loc. cit.) states that it minimises shrinkage and collapsed 

 cavities in mammalian embrvos. 



* By Peter Gray. 



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