61 



dichromate, 24 hours; 5. Running water, 24 hours; 6. Alcohols; 

 paraffin imbedding; 7. Sections 5^; 4% ferric alum for 24 hours; 

 8. Rinse in distilled water and 9. Place in a mixture of saturated 

 alcoholic solution of sodium sulphalizarinate 1 c. c., distilled water, 80 

 to 100 c. c., 24 hours; 10. Rinse away the stain with water; 11. 

 Stain on the slide with a freshly prepared mixture of saturated alcoholic 

 solution of crystal violet and aniline water, equal parts, warming 

 until it steams; 12. Rinse in w^ater and differentiate in 30% acetic 

 acid (1 minute or less) ; 13. Rinse in running water 5 to 10 minutes 

 to remove the acid, drying with blotting paper; 14. Dehydrate 

 rapidly in absolute alcohol, (dip); 15. Clear in bergamot oil and 

 xylene; 16. Mount in neutral balsam. 



The above method is capricious. The following method is recom- 

 mended: (1) fixing 12 to 24 hours in Zenker's fluid or the Copper 

 dichromate mixture ( 16) with 1/10% acetic acid only; (2) mor- 

 danting 3 to 4 days in 2.5% dichromate (or Muller's fluid or Erlicki's 

 fluid respectively); (3) paraffin imbedding; (4) using iron or copper 

 hematoxylin as the stain ( 94, 95). Benda's fluid may be substi- 

 tuted for the fixer, and a number of other stains may be used; con- 

 sult [6, 30]. 



179. Secretion Granules in the cytoplasm, such as the zymogen 

 granules in the stomach and pancreas, granules of the suprarenal 

 medulla and Islands of Langerhans, etc., may be preserved and 

 demonstrated in the same manner and probably for the same general 

 reasons ; thus : 



1. Trypsinogen granules. Fix in 1% osmic acid which pre- 

 serves and browns them; or as under 2 below. 



2. Pepsinogen granules. Fix in Kelly's fluid or one of sim- 

 ilar composition. Iron hematoxylin or Weigert's copper hema- 

 toxylin, or neutral stains ( 107, 128, 131) may be used. 



3. Medulla of suprarenal. Apply similar fixation methods, e. g., 

 Kelly's fluid, and regressive staining with basic stains (e. g., iron or 

 copper hematoxylin, toluidin blue, etc.). 



CONNECTIVE TISSUE 



180. White (Collagenous) Fibers. Fuchsin acid is particularly 

 valuable. Three methods of applying it for the differential staining 

 of connective tissue follow : 



