236 THE MICROSCOPE 



tion of salt. They show the fibrillar structure of the matrix 

 (V. Ebner). 



Dissociating Solutions. 



These solutions dissolve or soften certain parts of a tissue 

 whilst other parts are left unaffected. The result is that the com- 

 ponent parts may be readily separated by teasing. The piece of 

 tissue ought not to be larger than a pea. The result is usually 

 effected in from twenty-four to thirty-six hours, though a much 

 shorter time will often suffice. 



Nitric Acid and Glycerine.~Mix one part of strong nitric acid 

 containing nitrous acid with three parts of water and one part of 

 glycerine. The object is placed in this mixture for two or three 

 days, and then removed to water. It is specially useful for isolat- 

 ing nerve-structures and lens-fibres (Freud). Osmic acid — "i per 

 cent, to I per cent., Miiller's fluid — is used for stomach and kidney. 



Hydrochloric and Sulphuric Acids.— For a fuller description 

 see "Hardening Solutions," p. 184. 



Dissociating Fluids. 



Iodised Serum.— Add iodine to blood-serum or amniotic fluid 

 if the fluid is of a distinctly yellow colour. This fluid dissolves 

 the cement-substance between cells in from one to two days. I find 

 the following a very good method : — Take white of egg^ i ounce ; 

 water, 9 ounces ; common salt, 2 scruples ; and add 6 drops of 

 concentrated tincture of iodine to each ounce while shaking the 

 mixture. If the solution becomes pale, a few drops more iodine 

 should be added. This may be also used as a normal fluid. 



Dilute Chromic Acid ('oi per cent.). — Dissolve one gramme 

 nitric acid in 10,000 cc. of water, or dilute i per cent, solution. 

 This does excellently for isolating the fibrillos of muscle, and for 

 the nerve-cells of the spinal cord. Two or three days' maceration 

 serves to bring about the result. 



Dilute Alcohol (" Alcool an tiers "). — Mix 2 parts of water 

 and I of rectified spirit. This is one of the most useful dissoci- 

 ating fluids, and requires one or two days for its action. 



