6 PREPARATION AND MOUNTING 



Concentrated sulphuric and hydrochloric acids, used cold, 

 cause epidermic structures to swell up, so that their cells 

 may be easily separated. 



Tannin, dissolved in water or recti6ed spirit of wine, 

 hardens gelatinous and albuminoid ^issues : it also makes 

 them shrink. Its solution in water has been used, as men- 

 tioned in another part of this treatise, as an injection pre- 

 liminary to one of coloured gelatine, to prevent extravasation 

 through the walls of the blood-vessels. It also colours the 

 tissues a fawn-colour, or a very faint brown. 



Lime water and baryta water, especially the latter, will, 

 according to Rollet, dissolve the animal cement by which the 

 fibres of connective tissue are held together. After a few 

 days' soaking such tissue, as well as tendon, may easily be 

 teamed out by needles. 



Oxalic acid, in a cold saturated solution (1 acid, 15 

 water), according to Schultze, " causes connective tissues tc- 

 swell up and become transparent, while those formed of al- 

 buminous substances become hardened and isolated. Ex- 

 tremely delicate elements of the body, such as the rods of 

 the retina, &c., are thus well preserved." 



Strong nitric acid mixed with chlorate of potash destroys 

 connective tissue in a short time, and is therefore a good 

 medium for isolating muscular fibres (Kuhne). 



Sulphuric acid, highly diluted (1 to 1,000 parts of water), 

 used warm, gelatinizes connective tissue, and is also useful 

 for the isolation of muscular fibres. 



Strong hydrochloric acid dissolves the intercellular sub- 

 stances of organs abounding in connective tissue. 



Ammonia acts on animal matters much in the same way 

 as potash and soda. 



Alcohol coagulates albuminous tissues, and makes them 

 opaque. It corrugates most transparent membranes, and 

 thus renders them more visible. 



Finally, it may be affirmed that there often exists a need 

 of making objects which are too dark more transparently 

 means of a fluid which permeates them un> qually, so that 



