340 PRACTICAL HISTOLOGY. [XXX. 



decolorised by the ferricyanide mixture, clarified, and mounted in 

 balsam (Hamilton). 



Stages of Weigert's Method. 



(1.) Harden nervous system in Miiller's fluid. 



(2. ) Harden in alcohol without previous washing in water. 



(3. ) Embed in celloidin. 



(4.) Place celloidin block in a half-saturated solution of copper acetate 



(24-48 hours). 



(5.) Alcohol, 70 per cent. (24 hours). 



(6.) Cut sections and stain them in Weigert's hfematoxylin (24 hours). 

 (7.) Wash in water. 

 (8.) Partially decolorise in ferricyanide fluid until grey matter becomes 



yellow. 

 (9.) Wash in water, dehydrate in absolute alcohol, clarify in xylol, and 



mount in xylol-balsam. 



Pal's method is referred to on p. 343, but the following combina- 

 tion of the Pal and Weigert method gives good results : 



5. Modified Weigert-Pal Method. 



(i.) Harden in Miiller's fluid and then in alcohol, without wash- 

 ing pieces in water. 



(ii.) Embed and cut sections in celloidin. 



(iii.) Wash in water and transfer to Marchi's fluid (5-10 hours), 

 (iv.) Wash and transfer for 10-16 hours to 



Kultschitzky's Hsematoxylin. 



Hfematoxylin ..... i gram. 

 Absolute alcohol .... 2-5 cc. 



Dissolve, and to the fluid add 



Acetic acid (2 per cent.) . . . 100 cc. 



The sections become black. 



(v.) Bleaching process (a.) Wash in water and bleach for 5 

 mins. in .2 per cent, permanganate of potash. Wash 

 again, and transfer to 



(b.) Pal's solution (p. 344), in which they are rapidly (5-10 

 mins.) bleached, the medullated fibres alone remaining 

 black. 



(vi.) Wash in water, dehydrate in alcohol, balsam, oil (xylol), 

 balsam (Schafer). 



6. Weigert-Stained Cord. (a.) (Land H) Observe the medulla 

 of the medullated nerves, stained purplish. There are so many fine 

 medullated nerve-fibres revealed in the grey matter that it is impos- 

 sible to reproduce their complexity in a woodcut. The nerve-cells 

 are not specially in evidence, although they can be stained with 

 picro-carmine. 



