670 PHYSIOLOGICAL CHEMISTRY. 



larly to produce local anaemia, and is called by various names : suprarenalm, 

 suprarenin, adrenalin, epinephrin. 



Desiccated suprarenal glands, Glandulae suprarenales siccse. These 

 are the cleaned, dried, and powdered suprarenal glands of the sheep or ox, 

 freed from fat. A light-yellowish, amorphous powder, partially soluble in 

 water. 



Brain consists of so many individual parts that the analysis of it 

 as a whole is of little value, and to separate these parts successfully 

 is a task not yet accomplished. Brain, as a whole, contains lecithin, 

 cholesterin, protagon, and many other substances, some of which are 

 distinguished by the large quantity of phosphorus they contain. 



The gray matter contains albumin, globulin, nucleoprotein, and nuclein. 

 Neurokeratin forms the neuroglia. In the white matter is found protagon, a 

 very complex substance containing nitrogen and phosphorus. It yields on 

 hydrolysis a lecithin, fatty acid, and cerebroside. The cerebrosides are nitro- 

 genous substances free from phosphorus, yielding on hydrolysis galactose, 

 sometimes called brain-sugar. Fused with caustic potash, or boiled with nitric 

 acid, they form palmitic or stearic acids. Three cerebrosides are known: 

 cerebrin, kerasin, and encephalin. 



The term " lipoids :> is applied to an indefinite group of organic substances, 

 which are, like the fats, soluble in ether and alcohol. These substances are 

 present in many kinds of tissue, and are particularly abundant in the brain 

 and in nerve fibres. The more important membranes are cholesterin and the 

 phosphorized fats (phosphatides, lecithins). The cerebrosides are also classed 

 here. The function of these substances is entirely unknown. Their abun- 

 dance in brain tissue is the basis of the well-known theory that the anaesthesia 

 produced by ether and chloroform is due to the solvent action of these sub- 

 stances upon the lipoids. 



Lecithins, C^H^NPOg or C 42 H 84 NPO 9 . Lecithin, one of the con- 

 stituents of bile, is a member of the group of substances generally 

 termed phosphorized fats or lecithins. These bodies are highly com- 

 plex in composition, and may be looked upon as fats formed f Von/ 

 glycerin-phosphoric acid by substitution of hydrogen atoms with two 

 fatty acid radicals and a base, choline. 



Glycerin-phosphoric acid, C 3 H 5 <^ QpQ 2 QTj\ ^ s obtained by the 



action of glycerin on phosphoric acid, when combination takes place 

 with elimination of water, thus : 



C 3 H 5 (OH) 3 + H 3 P0 4 C 3 H 5 (OH) 2 .H 2 P0 4 + H 2 O. 



Glycerin-phosphoric acid is a syrupy liquid yielding easily soluble 

 salts, some of which are used medicinally. The hydroxyl hydrogen 

 is replaceable by acid radicals and the hydrogen of phosphoric acid 

 by bases. Thus, by introducing the radicals of stearic acid and 

 of choline distearyl-lecithin is obtained of the composition, C 3 H 5 

 (C 18 H 35 2 ) 2 .HP0 4 .C 2 H 4 N(CH 3 ) 3 OH. 



