170 
Lecithin. 
f  Am.  Jour.  I'liann. 
|      April,  1U14. 
Baumstark,  Ruppel,  Kossel  and  Freytag,  is  a  combination  of  leci- 
thin with  cerebrosides.5  Protagon  is  described  by  Kossel,  Ruppel 
and  others  as  a  crystalline  substance,  soluble  in  hot  alcohol  and 
which  swells  up  in  water. 
Physiology  of  Lecithin. 
Special  attention  has  been  paid  to  the  study  of  the  origin  and 
significance  of  lecithin  in  the  vegetable  world  by  Maxwell,  Stoklasa, 
Staniski,  Marchlewski,  Hanai  and  Koch.  Even  though  the  results 
of  their  investigations  have  not  rendered  the  chemistry  of  lecithin 
formation  as  clear  as  might  be  desired,  yet  they  have  shown  that 
lecithin  may  and  usually  does  occur  in  all  parts  of  plants.  From 
this  fact  alone  it  may  be  concluded  that  it  is  a  very  important  or 
indispensable  body  in  the  plant. 
Maxwell  attempted  to  prove  that  the  phosphorus  present  in  seeds 
in  an  organic  form  was  changed  during  germination  to  the  organic 
form,  during  which  process  lecithin  was  produced.  The  interme- 
diate stages  passed  through  by  the  phosphoric  acid  are  unknown. 
In  the  transition  from  the  vegetable  to  the  animal  kingdom  the 
organic  combination  is,  in  the  author's  opinion,  retained.  The 
lecithin  of  a  hen's  egg,  on  the  other  hand,  changes  when  the  egg 
is  hatched  into  inorganic  phosphorus  compounds,  and  as  a  mineral 
phosphate  plays  a  part  in  the  bone-formation  of  the  developing 
animal.  But  in  the  later  stages  of  hatching,  as  Maxwell  showed, 
the  opposite  process  may  occur.  The  most  interesting  fact  brought 
out  by  Maxwell's  researches  is  that  the  animal  organism  is  capable 
of  changing  inorganic  phosphorus  into  organic  compounds.  As  in 
the  opinion  of  some  observers,  to  which  reference  will  be  made  later, 
the  lecithin  ingested  with  the  vegetable  food  is  decomposed  in  the 
animal  intestine  and  absorbed  as  phosphoric  acid  (glycerophosphoric 
acid),  lecithin  synthesis  must  occur  in  the  animal  and  human  organ- 
ism, for  it  would  otherwise  be  impossible  to  explain  the  origin  of  the 
richness  in  lecithin  of  the  animal  organism.  Reicher  has  recently 
also  favoured  this  opinion. 
Stoklasa,  from  his  own  observations,  formed  the  opinion  that 
by  far  the  greater  part  of  the  phosphoric  acid  of  plants  was  present 
6  Cerebrosides  are  bodies  containing  nitrogen  but  no  phosphorus,  which 
on  hydrolysis  produce  sugar. 
