MEDICAL AND BIOLOGICAL STAINING TECHNIQUES 



Formula: 



Chromic acid . . .. .. .. 1-5 gm. 



Acetic acid 10% aqueous . . . . 100 ml. 



Distilled water . . . . . . 60 ml. 



Formalin (formaldehyde 40%) . . 40 ml. 



Note. — The formaldehyde should not be added until the solu- 

 tion is required for immediate use. 



Technique: 



Fix material for one to two days; then wash twelve to sixteen 

 hours in running water. Dehydrate ; clear and embed. 



Orth's Fluid 



Recommended for : 



Demonstration of acute degenerative processes to be stained 

 with Giemsa, Wright, or Leishman Stain, and for Intestine. 



Formula: 



Potassium dichromate . . . . 2-5 gm. 



Sodium sulphate crystals . . . . i gm. 



Distilled water . . . . . . 100 ml. 



Formalin (formaldehyde 40%) . . 10 ml. 



The last item should not be added until the fixative is required 

 for immediate use. 



Technique: 



Fix pieces of tissue up to i cm. in thickness for two to four days ; 

 then wash in running water from twelve to twenty-four hours. 

 Transfer to 80% alcohol; dehydrate; clear and embed. 



Remarks: 



This fixative may be employed as a general fixative for animal 

 tissues. It is useful where a firm consistency of tissue is required, 

 but it is not recommended for sharp histological detail. The value 

 of the sodium sulphate in the above formula is extremely doubtful 

 and it appears that this constituent may be left out without any 

 noticeable effect. 



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