-470 PRACTICAL ORGANIC AND BIO-CHEMISTRY 



Mucin of Slugs. 



The sticky mass, obtained by irritation of the mantle, is milky in 

 appearance owing to the presence of calcium carbonate ; it is put into '01 per 

 cent, caustic potash solution. The mucin is precipitated by acetic acid. 

 Solution and precipitation are repeated several times. 



This mucin resembles the mucin of the submaxillary gland. It is not 

 soluble in -i--2 percent. HC1. 



Another mucin has been obtained from the foot of the slug. 



Mucin of Fish Eggs. 



The eggs are treated with water and the aqueous solution is diluted and 

 hydrochloric acid added until "3 per cent, is present. (The ichthulin is 

 not precipitated.) The precipitate is washed, dissolved in dilute alkali and 

 thrown down with acid several times. 



This mucin is similar to submaxillary mucin in being insoluble in 'i per 



cent, hydrochloric acid. 



Pseudomucin. 



Pseudomucin is present in ovarian cysts and is whitish and slimy in 



appearance. The cysts are treated with alcohol and the stringy precipitate 



which is formed collects on a glass rod on stirring, it is ground up under 



. alcohol, washed with ether and dissolved in water. The solution is precipitated 



with alcohol. 



Pseudomucin forms a nearly colourless powder giving an opalescent 

 solution with water. Acetic acid forms a turbidity but no precipitate. The 

 solution is precipitated by tannic acid, hydroferrocyanic acid and basic lead 

 acetate. About 30 per cent, of reducing carbohydrate is formed on hydrolysis. 



Paramucin. 



The solid, pale yellow, glistening substance found in many ovarian cysts 



; has been termed paramucin. The mass is treated with alcohol containing 



hydrochloric acid, alcohol and ether. The mass contracts and can be 



obtained in this way as a powder. 



It is insoluble in water, swells up in alkali becoming gelatinous and 

 slowly dissolves. The solution behaves like solutions of mucin. Acetic acid 

 produces a precipitate which is soluble in excess. 



It yields about 10 per cent, of reducing carbohydrate on hydrolysis. By 

 . pepsin digestion Leathes has isolated a protein-free substance termed para- 

 mucosin. 



Mucin of the Cornea (Corneomucoid). 



The cornea is freed from epithelium and treated with water or very dilute 

 alkali. The solution is acidified with acetic acid. 



Corneomucoid is insoluble in water, but dissolves in alkali. Its solutions 



behave like mucin solutions, but are not slimy. 



Mucin of the Lens (Hyalomucoid). 



The liquid of the lens is filtered, diluted with 2-3 volumes of water 

 and acetic acid added until i per cent, is present. The precipitate closely 

 resembles Corneomucoid. 



Chondromucoid. 



Finely divided cartilage is extracted at 40 with water : hydrochloric acid 

 is added to the solution until it contains -2 --4 per cent, and it is warmed 

 on the water-bath. A white flocculent precipitate gradually separates out. It 

 is dissolved in water containing a trace of alkali and is purified by precipitation 

 with hydrochloric acid. 



It is a colourless powder having an acid reaction and is insoluble in water. 



It is precipitated from its solution in alkali by acetic and dilute mineral acids. 



It is not precipitated by mercuric chloride or tannic acid, but copper sulphate 



and lead acetate precipitate it. Chondroitin sulphuric acid is formed by 



1 peptic digestion. 



