Am.  Jour.  Pharm.  ) 
April,  1914.  j 
Lecithin. 
173 
probably  nothing  to  do  with  fat,  with  which  others  often  consider  it 
to  be  in  relation.  Like  Koch,  he  seeks  the  function  of  lecithin  in  the 
cell  primarily  as  an  oxygen  carrier,  but  also  in  the  colloidal  char- 
acter of  the  phosphatides,  "  for  the  substratum  of  life  itself,  proto- 
plasm, which  is  still  in  many  respects  so  enigmatical,  is  a  colloid." 
The  physiological  significance  of  the  fatty  acids  contained  in 
lecithin  and  of  choline  is  explained  by  Koch.  According  to  him, 
the  lecithins  are  of  importance  for  the  life  of  the  celi  in  two<  ways. 
For  in  conjunction  with  the  albumins  in  colloidal  solution,  they  con- 
stitute the  basis  for  the  formation  of  the  necessary  viscosity,  on 
account  of  the  ease  with  which  they  are  influenced  by  ions  (Na,  Caj. 
Further,  by  means  of  their  unsaturated  fatty  acids  they  take  part 
in  oxygen  metabolism,  and  by  their  methyl  groups,  which  are  com- 
bined with  nitrogen,  in  other  reactions  not  yet  known.  Phosphoric 
acid,  although  in  some  respects  the  nucleus  of  the  whole,  does  not, 
in  Koch's  opinion,  play  any  part  in  metabolism ;  Halliburton  has 
shown  that  the  amount  of  phosphorus  in  degenerated  nerves  does 
not  begin  to  decrease  before  the  eighth  day.  The  author  explains 
the  fact  that  the  residues  of  the  unsaturated  fatty  acids  are  capable 
of  taking  part  in  oxygen  metabolism  by  the  ease  with  which  they 
are  oxidised ;  this  is  also  known  to  be  the  case  with  lecithin  which 
has  been  in  contact  with  the  air  for  some  time.  But  it  has  not  yet 
been  proved  that  the  lecithins  may  be  regarded  as  oxygen  carriers. 
The  physiological  significance  of  the  nitrogen  group  may,  according 
to  Halliburton,  be  recognised  by  the  fact  that  in  certain  diseases  of 
the  nervous  system,  such  as  general  paralysis,  a  considerable  amount 
of  choline  passes  into  the  cerebrospinal  fluid. 
As  in  the  vegetable  kingdom,  so  in  the  animal  kingdom,  lecithin, 
as  I  mentioned  above,  is  present  in  almost  every  organ.  It  is  present 
in  comparatively  large  amounts  in  the  principal  organs,  and  the 
conclusion  may  consequently  be  drawn  that  it  also  performs  impor- 
tant functions  in  the  economy  of  the  animal  cell.  The  nature  of 
these  functions  cannot  be  stated  with  certainty.  Nor  has  it  been  con- 
clusively ascertained  whether  lecithin  is  formed  in  the  animal  or- 
ganism, whether  it  is  ingested  with  the  food,  or  whether  both  these 
processes  take  place.  The  results  of  the  investigations  of  various 
observers  afford  some  elucidation  of  the  matter. 
Bokay  found  that  lecithin  was  split  up  in  the  intestine  by  the 
fat-splitting  ferment  of  the  pancreas,  or  putrefactive  ferment,  into 
fatty  acids,  choline  and  glycerophosphoric  acid.    As  he  was  unable 
