AmNo°vur i92iarm'  \  Chemical  Elements  of  Living  Matter.  753 
Content  of  Na20  in  the  Ash  of  Plants: 
100  parts  of  ash  contain  Na20 
in  roots,  average  2-10% 
in  stems,  average  1-4% 
in  leaves,  average  0.8-2% 
in  seeds,  average  0.6-2% 
16.  Calcium  is  widely  distributed  in  animals  and  plants  and  is 
important  in  regulating  biochemical  reactions  through  irritability 
and  stimulation  ■  e.  g.,  in  vertebrates  the  clotting  of  blood,  in  plants 
the  protein  formation  of  calcium  proteids,  nucleo-proteins,  and  plas- 
tides  of  cell.  In  vertebrates  the  skeletal  material  is  chiefly  calcium 
phosphate,  in  invertebrates  calcium  carbonate.   There  are  in 
muscles  .005%  CaO  pancreas  0.15%  CaO 
blood  .006%  lungs  .016% 
brain  .009%  liver  .029% 
kidney  .009%  heart  -025% 
In  the  plant  organism  it  accumulates  in  leaves  and  vegetative  organs 
and  there  appears  to  be  a  relation  between  the  Ca  content  and  car- 
bohydrate digestion. 
Content  of  CaO  in  the  Ash  of  Plants: 
100  parts  of  ash  contain  CaO 
in  roots  2-11% 
in  stems  5~25% 
in  leaves  6-32% 
in  seeds  2-9% 
ij.  Manganese  always  appears  in  traces  in  animals  and  plants. 
It  is  found  not  only  in  blood  (0.5-2.5  mg.  per  liter),  milk  bones, 
hairs,  tissues  of  mammals,  but  also  in  the  ash  of  plants.  Man- 
ganese salts  have  recently  been  considered  as  fertilizer  for  plants,5 
but  their  role  in  the  metabolism  is  little  understood.  They  seem  to 
act  as  stimulants  and  irritants  by  regulating  the  motor  activities  of 
the  cell  organism.  The  large  amount  of  Mn  in  the  ash  of  thex  pan- 
creas (2.2-2.5%)  is  remarkable. 
18.  Aluminum  is  abundant  in  soil  and  therefore  widely  distrib- 
uted in  plants.  Cryptogams  contain  Al  mainly  in  their  stems,  while 
angiosperms  have  much  Al  in  their  blossoms  and  flowers.  Pine 
needles  are  especially  rich  in  aluminum. 
5  U.  S.  Dept.  Agricult,  Bull.  600,  1917. 
