APPENDIX TO THE HISTOLOGICAL SECTION. Ill 



filtrate to dry ness. The dried residue has the colour of red ochre, 

 and should dissolve completely in distilled water. Use a 1 P- C - solu- 

 tion or stronger ; add thymol to keep it. 



20. Hsematoxylin. Kleinenbepg-'s formula. Stock solutions. 

 1. Saturated solution of calcium chloride in 7<)P- C - alcohol containing 

 alum in excess ; filter when wanted. 2. 'Saturated solution of alum in 

 70 1'- - alcohol. 3. Saturated solution of hamiatoxylin crystals in abso- 

 lute alcohol. Add 1 part of No. 1 to 8 parts of No. 2, then a few drops 

 of No. 3 until a moderately deep purple colour results. This keeps 

 almost indefinitely without depositing. The reddish colour turns to 

 the characteristic violet on the addition of water. It stains rapidly, 

 and is especially useful for staining on the slide. Diluted with 3 or 

 5 volumes of No. 2 it stains well in bulk. Small pieces of tissue. 



21. Heidenhain's Hsematoxylin stain. A bulk stain. 1. A 0'5i )C 

 solution of luematoxylin crystals in distilled water. 2. A 0'3P- C - solution 

 of neutral chromate of potassium in water. Small pieces of glands, 

 hardened in absolute alcohol are placed in Nos. 1 and 2 successively, 

 in each for 12 to 24 hours, are then washed in water, treated in alcohol, 

 and cut in paraffin. The colour is steel grey. 



22. Haemalum. Hsematein can be purchased, and a moderately 

 deep-coloured solution is made in a 10 P- C - solution of alum; or dissolve 

 haematoxylin crystals in strong ammonia, dry in air, and make a 

 solution as above. This is one of the best nuclear bulk stains. 

 Requires four or more days, according to the density and size of the 

 tissue treated. It does not overstain. Followed by increasing 

 strengths of alcohol to the last of them, a small quantity of eosine 

 can be added to give a ground stain before passing the tissue into 

 cedar oil for paraffin embedding. 



23. Weig-ept-Pal method, Bolton's modification (Jl. Anat. and 

 Physiol., vol. xxxii., p. 264). For brain and spinal cord. 



1. Fixing and hardening. The tissue as fresh as possible is placed 

 in a large quantity of 5 P- C - formaldehyde (1 formol to 7 parts of 

 water). Change occasionally for six weeks ; may remain for six 

 months or longer. The tissue may be cut at the end of a week, but 

 the sections have a slight tendency to frill. 



2. Cutting. Freeze, without previous soaking, in gum. Keep the 

 sections in 5 P- C - formaldehyde until wanted. 



3. Mordanting. Sections are placed in one of the following : 

 Ferric ammonium sulphate (iron alum) 2P-% osmic acid 1 P- C - (for other 

 mordants see original paper). The former yields ultimately a blue 



