578 BRAIN AND NERVES. 



ordinary temperature, and that as shown by ROSENHEIM and TEBB, on 

 dissolving in pyridine at 30 C. and heating or cooling the solution deposits 

 a precipitate of a substance rich in phosphorus. Although we generally 

 consider the phosphorized component of protagon as lecithin, still, accord- 

 ing to ROSENHEIM and TEBB it is probably a diamido-phosphatide, 

 called sphingomyelin by THUDICHUM. On boiling protagon with dilute 

 mineral acids it yields a reducing sugar (galactose) due to the decompo- 

 sition of the cerebrosides. 



Protagon appears, when dry, as a loose white powder. It dissolves 

 in alcohol of 85 vols. per cent at 45 C., but separates on cooling as a 

 snow-white, flaky precipitate, consisting of globules or groups of fine 

 crystalline needles. It decomposes on heating even below 100 C. It is 

 difficultly soluble in cold alcohol or ether, but dissolves, at least when 

 freshly precipitated, in ether on warming. It dissolves in methyl alcohol 

 containing chloroform and, as above stated, separates cerebroside. Pro- 

 tagon is soluble in pyridine at 30 C., yielding a clear solution, and this 

 solution has a specific rotation (a') D = +6.8 ( WILSON and CRAMER). On 

 warming or cooling according to ROSENHEIM and TEBB, the rotation 

 changes with the separation of sphingomyelin so that it first diminishes 

 in rotation, then is zero, and then becomes strongly levorotatory until 

 it reaches 242, and finally, when nearly all the sphingomyelin has 

 separated out it becomes constant at about 13.3. The strong levo- 

 rotation depends upon the accumulations of doubly refracting spheroid 

 crystals of sphingomyelin. With little water protagon swells up and 

 is partly decomposed. With more water it forms a jelly or pasty-like 

 mass which, with the addition of considerable water, forms an opalescent 

 liquid. On fusion with saltpeter and soda it yields alkali phosphate. 



Protagon can be prepared in the following way: The finely ground 

 brain-mass, as free as possible from blood and membrane, is dehydrated, 

 which is best done by cold acetone or by grinding with burnt plaster-of- 

 paris or anhydrous sodium sulphate, and then extracted with ether. 

 The mass is then extracted at 45 C. with 85 vol. per cent alcohol until 

 the filtrate when cooled to C. gives no more precipitate. All the 

 precipitates obtained on cooling to C. are extracted with ether and 

 recrystallized from alcohol. Further details can be found in the cited 

 works of CRAMER, WILSON, GIES, ROSENHEIM and TEBB. 



Cerebrosides or Cerebrins. 



On decomposing protagon (or the protagons) by the gentle action of 

 alkalies we obtain, as cleavage products, as above stated, one or more 

 bodies which THUDICHUM has embraced under the name cerebrosides. 

 The cerebrosides are nitrogenous substances free from phosphorus, which 

 yield a reducing variety of sugar (galactose) on boiling with dilute mineral 



