290 THE ESSENTIALS OF HISTOLOGY. 



APPENDIX. 



General Methods of Preserving and Hardening Tissues and Organs. 

 The fluids which are most commonly used are alcohol, chromic acid solution 

 (1 in 200 to 1 in 500, to which glacial acetic acid may advantageously be 

 added in the proportion of 2 parts acetic acid to 1000 chromic solution), picric 

 acid solution (saturated, either alone or containing 2 parts of sulphuric acid 

 to 1000), osmic acid solution (1 per cent.), bichromate of potash solution (2 

 per cent.), Miiller's fluid (bichromate of potash 2J parts, sulphate of soda 1 

 part, water 100 parts), Erlicki's fluid (which is the same as Miiller's, but with 

 sulphate of copper in place of sulphate of soda), and bichromate of ammonia 

 (2 per cent.). For preserving the structure of cells and nuclei the best 

 general fixing and hardening fluid is that recommended by Flemming. This 

 consists of 15 vols. of 1 per cent, chromic acid, 4 vols. of 2 per cent, osmic 

 acid, and 1 vol. glacial acetic acid. It may advantageously be diluted with 

 from two to five times its bulk of water before use. The following methods 

 of hardening the several tissues and organs are found to give good general 

 results : 



Tissue or Organ. Hardening Fluid. 



Bladder Chromic acid or alcohol. 



Blood-vessels .... Alcohol or bichromate of potash. 

 Brain ..... Bichromate of ammonia or Miiller's 



fluid. 



Elastic ligament . . . Bichromate of potash. 

 Embryos ..... Chromic acid or picric acid. 



Eye Miiller's fluid. 



Eyelids ..... Alcohol. 



Ganglia Picric acid or Miiller's fluid. 



Heart ..... Alcohol or bichromate of potash. 

 Injected organs . . . Alcohol. 



Intestine ..... Distend with chromic acid or with 



a mixture of equal parts alcohol 

 and I per cent, chromic acid solu- 

 tion, or with picric acid. 



Kidney Miiller's fluid. 



Lachrymal gland . . . Alcohol. 



Larynx Chromic acid. 



Liver Miiller's fluid. 



