MEDICAL AND BIOLOGICAL STAINING TECHNIQUES 



2. Transfer to acetone and leave for several days to dissolve out 

 the fats which would otherwise stain intensely and obscure the 

 view of the bony structures. 



3. Wash well with 95% alcohol; then immerse in 95% alcohol 

 for twenty-four hours. 



4. Immerse in Solution A from one to seven days, according to 

 the size of the specimen, until the bones are clearly visible through 

 the muscle. 



5. Transfer to Solution B until the bones are stained the desired 

 depth of colour ; this takes from one to seven days, and the solution 

 should be changed on the fourth day. 



6. Clear in Solution C until no more colour comes out. 



7. Pass into a mixture of equal parts of glycerin and water, and 

 continue through increasing strengths of glycerin. 



8. Store in pure glycerin. 



Results: 



Bones are stained red ; soft tissue, transparent and unstained. 



Notes: 



If the initial clearing in potass, hydroxide solution has pro- 

 gressed to the proper stage only the bone will be stained, but 

 otherwise soft tissue will also be stained. 



The prolonged preliminary fixation in alcohol renders the tissue 

 less liable to maceration in the potass, hydroxide solution. 



Objects fixed in liquids other than alcohol may be stained by this 

 method provided they are soaked in 90% alcohol for at least three 

 days. The best preparations are made with fish, but amphibia and 

 mammals have also been tried with a fair degree of success, although 

 there is not the same firm consistency about the flesh of a mammal 

 or amphibian, prepared by this technique, as there is with that of 

 a fish. 



The technique is particularly suitable for demonstrating 

 developing bone. 



William's modification of Dawson's method 



This technique is particularly suitable for mammalian embryos 

 and mature specimens of Urodele amphibians ; for distinguishing 



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