Am.  Jour.  Pharm. 
Nov.,  1921. 
£  Chemical  Elements  of  Living  Matter. 
751 
Content  of  K20  in  the  Ash  of  Plants: 
100  parts  of  ash  contain 
K20 
in  roots,  average 
in  stems,  average 
in  seeds,  average 
in  leaves,  average 
45-60% 
13-47% 
23-42% 
26-36% 
Certain  fresh  water  and  marine  plants  are  able  to  store  large  quan- 
tities of  potash,  e.  g.}  the  Pacific  Coast  Kelps  (Phaeophyceae).  A 
small  percentage  can  be  substituted  by  the  other  alkali  metals.- 
Potassium  occurs  mainly  in  the  cell-membranes  and  tissues  and 
seems  to  act  as  osmotic  agent.  The  saps  and  juices  sometimes 
contain  K  which  may  be  replaced  by  sodium. 
ELEMENTS  WHICH  COMMONLY  OCCUR  IN  CELL  ORGANISM. 
10.  Fluorine  is  found  in  small  amounts  in  bones  (0.05-0.2%, 
of  ash),  teeth"  (0.18%  of  ash),  brain  matter  (0.8  mg.  in  100  gm.), 
cow's  milk  (0.3  mg.  in  1  liter),  egg-yolk  (1.1  mg.  in  100  gm.).  It 
occurs  also  in  blood  where  it  seems  to  play  a  protective  and  regu- 
lative part  in  the  process  of  coagulation  of  fibrin.  It  is  also  found 
in  certain  mollusks  and  many  plants. 
11.  Chlorine  because  of  its  abundance  in  sea-water  is  present 
in  marine  algae  and  many  other  plants,  though  it  seems  to  be  not 
essential  for  the  complete  development  of  higher  plants.  It  is  essen- 
tial to  animals,  occurring  mainly  as  NaCl  in  blood,  lymph,  tears, 
sweat,  and  urine.  As  free  HC1  of  the  gastric  juice,  it  takes  part 
in  the  digestion  of  food.  The  percentage  of  Chlorine  in  different 
tissues  is 
blood  0.268%  spleen  0.107%  bonemarrow  0.034% 
lungs  0.150%  brain  .100%  muscles  -033% 
skin  0.145%  stomach  .093:%  liver  ^.025% 
kidney  .122%  intestine  .040%  bile  .010% 
12.  Bromine  occurs  in  traces  in  all  organs  of  mammals.  It  is 
abundant  in  marine  algae,  but  little  is  known  of  its  function. 
13.  Iodine  is  essential  to  vertebrates  as  a  constituent  of  iodo- 
thyrin  of  the  thyroid  gland.  The  amount  of  I  in  the  gland  is  vari- 
able from  0.077-3.85  mg.  of  iodine  per  1  gm.  of  the  dry  substance 
