30 STUDENTS HISTOLOGY 



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WEIGERT-PAL H^MATOXYLIN METHOD 



This stain is employed for nervous tissues containing medullated 

 nerve -fibers. The medullary sheaths of these fibers are stained 

 intensely black, while the other elements of the tissue remain pale. 

 It is used chiefly for the spinal cord and the brain. 



The tissue is first hardened in Miiller's fluid. Unless the pieces 

 of tissue are very small, the hardening requires months. The 

 fluid must be changed frequently. Hardening is completed in 

 strong alcohol, without washing in water. Imbed in celloidin. 



The sections are overstained with haBmatoxylin, and subse- 

 quently are partly decolorized. The medullary sheaths retain the 

 stain with greater tenacity than the other elements of the tissue. 

 The solutions used are as follows: 



Hsematoxylin crystals 1 gram. 



Alcohol 10 c.c. 



Water 90 c.c. 



Boil and filter. Allow the solution to stand a week or two. If 

 used sooner, add a drop of saturated solution of lithium carbonate 

 to a part of the stain in a small dish. 



Permanganate of potassium 1 gram. 



Water 400 c.c. 



One per cent, solution of oxalic acid. 



One per cent, solution of sodium or potassium sulphite. 



Mix the oxalic acid and sodium sulphite in equal parts at the 

 time of using. Sulphurous acid is formed. 



The steps in staining are as follows: 



a. Sections are placed in the haematoxylin for twenty -four 

 hours, and are intensely stained, becoming nearly black. The pro- 

 cess may be hastened by letting them stand in an incubator, where 

 they may be sufficiently stairned in a few hours. 



6. Wash in water. 



c. Place the sections in the permanganate of potassium until 

 they acquire a dark brown color (one -half to five minutes). 



d. Wash in water. 



e. Place the sections in the mixture of oxalic acid and sodium 

 sulphite. The brown color should give way to a blue black in the 

 white matter, while the gray matter becomes nearly white. If the 

 sections remain too dark they may be returned to the permanganate 



