METHOD X. 



THE IRON-H^MATOXYLIN METHOD. 



A haematoxylin method for nerve material preserved in 

 formalin. Differential for the medullary sheath and also stains 

 the nerve cell. Especially adapted to the central nervous 

 system to show the course and occurrence of meduUated fiber 

 tracts. 



REAGENTS REQUIRED. 



A. Fixing agent (^10 per cent, formalin). — 



Formalin (40 per cent, formaldehyde, com.), 10 cc. 

 Distilled water, 100 cc. 



B. Mordant (4 per cent, iron alum). — 



Ammonio-ferric sulphate (Iron alum), 4 g. 

 Distilled water, 100 cc. 



C. Stain (0.5 per cent, haematoxylin). — 



Haematoxylin crystals, 0.5 g. 

 Distilled water, 100 cc. 



D. Counterstain (aqueous orange G.). — 



Orange G. (Griibler's), 0.5 g. 

 Distilled water, 100 cc. 



E. Ether-alcohol, thin celloidin, and thick celloidin will be 

 required for imbedding, and also a clearing fluid for celloidin 

 sections. For formulae see IX, D, E, and F, p. 55. 



PROCEDURE. 



I. 'Yo fix, carefully remove the fresh tissue and place in about 

 20 times its volume 10 per cent, formalin (A). Tightly close the 

 vessel and let remain for 2-5 days. 



Note. — Two days is the minimal time. The tissues in bulk may remain 

 in 10 percent, formalin indefinitely, and pieces of required size may be taken 

 from time to time as occasion demands. Tissue thus preserved will be found 

 also available for several other methods. 



The nervous system of the foetus can more easily be 



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