Am.  Jour.  Pharm.  \ 
April,  1914.  J 
Lecithin. 
.OH 
C3H5^OH 
\CK  Glycerophosphoric  acid. 
OH^P=0 
OH/ 
which  the  hydrogen  atoms  of  the  hydroxyls  of  glycerin  are  replaced 
by  fatty  acid  radicles,  and  one  hydrogen  of  the  phosphoric  acid 
residue  by  a  choline  radicle.  Theoretical  consideration  shows  that 
two  possible  formulas  exist,  one  symmetrical  and  one  asymmetrical, 
according  to  the  position  of  the  fatty  acid  residues  in  the  glycerin, 
thus : 
/O .  R  /O  .  R 
C3H5^0 .  R  CHee-O- 
Vk  \0 .  R 
/C^-°o^0  oh:,p=o 
\OH 
Since  lecithin  is  optically  active  and  as,  according  to  Willstatter 
and  Liidecke  and  also  according  to  Power  and  Tutin,  the  glycero- 
phosphoric acid  derived  from  lecithin  possesses  rotatory  power, 
Ulpiani  expressed  himself  in  favour  of  the  asymmetrical  formula. 
Speculations  of  this  kind  are,  of  course,  only  of  theoretical  interest. 
Possibly  the  synthesis  of  the  lecithins,  which  has  not  as  yet  been 
successfully  carried  out,  will  throw  light  on  the  question  of  the 
constitution  of  lecithin.  Hundeshagen,  as  the  result  of  an  unsuc- 
cessful synthesis  of  lecithin,  claimed  to  have  proved  the  truth  of 
Strecker's  statement  that  lecithin  was  not  a  salt  of  di-stearyl-glycero- 
phosphoric  acid  and  choline,  but  an  ester-like  combination  of  the 
two  substances,  in  which  the  basic  character  of  choline  was  retained. 
The  choline  salt  of  di-stearyl-glycerophosphoric  acid  obtained  by 
Hundeshagen  had  quite  different  properties  than  lecithin.  Kade's 
attempts  to  prepare  lecithin  synthetically  must  also  be  regarded  as 
failures  from  a  practical  point  of  view. 
Occurrence  of  Lecithin. 
Lecithin  is  so  widely  distributed  in  the  human  and  animal  organ- 
isms that  it  has  been  concluded,  though  not  without  contradiction, 
that  no  organ  exists  which  does  not  contain  lecithin.  Thus  the 
phosphatide    is    found,    according    to    Hermann,  Hoppe-Seyler, 
