APPENDIX 327 



PIGMENT. 



Destruction of pigment. Put the hardened piece of tissue in 

 a mixture of 



1 p.c. chromic acid 70 c.c. 

 Nitric acid 3 c.c. 



Water 200 c.c. 



for ^ a day to 2 days, and wash out well with water (both best 

 done in dark). Sections to be similarly treated should be stuck 

 to the slide with albumin. 



GLYCOGEN, cp. p. 182. In tissues hardened in osmic acid, 

 glycogen is not extracted by water, or very incompletely ; it may 

 be extracted by treating the sections with a diastatic ferment. 



FIBRIN. The tissue is hardened in alcohol. A section is 

 placed for about 10 minutes in a strong solution of gentian- violet 

 in aniline, washed in water and transferred to a slide. Here it 

 is gently pressed with blotting-paper, covered with iodine in 

 potassic iodide (p. 298) for two or three minutes; blotted; 

 decolourized with aniline 2 pts. and xylol 1 pt. ; blotted, the 

 aniline xylol washed out with xylol; mounted in balsam. 



CHITIN in tissues becomes hard in the process of imbedding in 

 paraffin ; in order to soften it place the tissue to 1 day in the 

 following mixture : 



Nitric acid 16 parts. 



5 p.c. chromic acid 16 



HgCl 2 sat. sol. in 60 p.c. alcohol 24 



Sat. aq. sol. picric acid 12 



Absolute alcohol 42 



AMYLOID SUBSTANCE. The tissue is best hardened in alcohol. 

 Amongst other methods, the sections may be stained with 

 methyl-violet, washed in dilute hydrochloric acid and mounted 

 in glycerine. The amyloid substance stains a reddish tint. 



