302 



Rosenheim and Tebb 



was At once cooled on ice to room temperature (15° C.) and the precipitate 

 filtered either after a few minutes or in some cases after half an hour. The 

 filtrate was poured into two volumes of acetone, which produced a small 

 quantity of a flocculent precipitate. After the removal of the latter by 

 filtration, the acetone-pyridine solution was cooled on ice, by which process 

 the bulk of the dissolved product was brought down. 

 The results of the analysis are given below : — 



Original " protagon "... 



Fraction 1. (insoluble in pyridine 

 at +15') . . '. 



Fraction II. (precipitated by ace- 

 tone at ± 0°) . 



These resultiS furnish the most striking proof for the composite nature 

 of " protagon." Under the conditions of the experiment a decomposition in 

 Wilson and Cramer's sense is impossible, and nevertheless "protagon" 

 is divided by one fractionation into a practically phoephorus-free part 

 and one with two and a half times as much phosphorus as that of the 

 original " protagon." The nitrogen figures also undergo characteristic 

 changes. 



(a) The phosphorus-rich constituents. — The quantity of this 

 fraction averages one-third of the " protagon " employed. We possess, 

 therefore, in pyridine a solvent by means of which the phosphorus-rich 

 moiety of " protagon " can be easily isolated. Its phosphorus percentage 

 is not appreciably raised by repeated (three times) recrystallisation from 

 pyridine, a fact which would, according to Wilson and Cramer, speak 

 for its definite composition. We have, however, succeeded in isolating its 

 main constituent, the di-amino-phospatide, sphingomyelin, by a fractiona- 

 tion method with alcohol-chloroform and acetone, which we shall com- 

 municate later in detail. For the purpo.se of comparison with " protagon " 

 ^e give below a complete analysis of the purest preparation which we 

 succeeded in obtaining so far. We have, however, reasons for believing 

 that this substance, which agrees in its properties with Thudichum's 

 sphingomyelin, is not yet perfectly uniform 



Sphingomyelin (our analysis) 



** Protagon " (Wil»on and Cramer's analysis, sample D) 



(b) The phosphorus-free constituents. — Fraction II. as obtained 

 above may be easily rendered perfectly phosphorus-free by further re- 

 crystallisation from glacial acetic acid (Koch) or by the method indicated 

 previously. 



