492 APPENDIX IV. 



Alkalies, etc. 



(13) Ammonia (strong). 



(14) Fehling's solution, kept as stock. 



(15) Caustic potash (concentrated). 



(16) - (5 or 6 per cent.). 

 (16B) Potash in alcohol. 



Inorganic Salts. 



(17) Perchloride, Acetate, or Sulphate of iron. 



(18) Bichromate of potash (10 per cent, watery solution). 



(19) Chlorate of potash (crystals). 

 Organic bodies. 



(20) Akohol (absolute, or 90 per cent.). 



(20A) Methylated alcohol, old style (miscible with alcohol). 



(21) Ether. 



(22) Alkanet, root or tincture. 



(23) Aniline chloride (in alcohol). 



(24) Camphor. 



(25) Carbolic acid (phenol). 



(26) Gelatine. 



(27) Phloroglucin, or Cherry-wood extract. 



(28) Cane sugar. 



(29) Turpentine. 



PRESERVING FLUIDS. The best is methylated alcohol (old style), of which 

 a good supply should be kept. The material to be preserved for 

 future work should be completely covered. For work in nucleus 

 or protoplasm, absolute alcohol should be used. 



SOFTENING. Alcohol material, especially if old, is often brittle, and stems, 

 etc., are hard. Soften for twenty-four hours in 



(30) Half-and-half glycerine and meth. alcohol. 



If it seems desirable, the alcohol can be allowed to slowly evaporate, 



and the glycerine to concentrate. 

 HARDENING. Soft tissues can often be hardened for cutting by three days 



in methylated spirit. 



FIXING THE CELL-CONTENTS. For studies in nuclei or protoplasm it is 

 necessary to fix the cell-contents of the material, while quite fresh, 

 without allowing them to contract. The material must be in very 

 small pieces, so as to be rapidly permeable, and the fluid, except in 

 the case of osmic acid, must be one hundred times the bulk of the 

 material. The best fixing fluids are : 

 (20) Absolute (or at least 90 per cent.) alcoM. 

 (lOc) Chromic acid, 1 per cent., or chrom-acetic acid, 1 per cent. 



(31) Osmic acid, 2 per cent. 



(32) Chrom-osmium acetic acid, of varying strengths, prepared as 



required. 



(33) Picric acid (saturated watery). 



In chromic acid, chrom-acetic acid, or picric acid of the above strengths 



