502  Formation  of  Oxalic  Acid  in  Vegetation.  {Am'o™*\i%&Tm- 
in  greatest  abundance  in  the  leaves.  It  would  seem  therefore  that 
the  formation  of  oxalic  acid  takes  place  principally  duriDg  the  earlier 
stages  of  the  plant's  growth,  and  ceases  during  the  period  of  in- 
florescence. 
Chenopodium  Quinoa  yields  a  neutral  juice  which  is  almost  free  from 
nitrates,  but  contains  a  relatively  large  proportion  of  soluble  oxalates. 
In  the  early  stage  of  growth  (May  18th),  the  percentage  of  oxalic  acid 
was  3 '9,  and  the  bases  in  the  ash  (25*6  per  cent.)  were  far  more  than 
sufficient  to  neutralize  the  whole  of  the  acid.  When  the  plant  was 
in  full  vegetation  but  had  not  begun  to  flower  (June  12th),  the  oxalic 
acid  had  increased  in  proportion  to  the  growth  of  the  plant,  but  was 
very  unequally  distributed,  about  one  half  being  in  the  soluble  form. 
The  absolute  amount  was  greatest  in  the  leaves,  next  in  the  stalk,  and 
somewhat  less  in  the  roots  and  flowers,  but  the  relative  proportions  do 
not  differ  much  in  different  parts  of  the  plant.  When  the  plant  was 
in  flower  (July  17th),  there  was  a  considerable  absolute,  and  a  con- 
siderable though  smaller  proportional,  increase  in  the  amount  of 
oxalic  acid,  which  was  still  at  a  maximum  in  the  leaves,  and  was  also 
abundant  in  the  flowers.  The  proportion  of  soluble  oxalates  becomes 
greater  and  greater  in  passing  from  the  stalks  to  the  leaves,  and  from 
the  leaves  to  the  flowers.  All  the  parts  contain  no  deficiency  of  cal- 
cium, but  the  insoluble  oxalates  predominate  in  the  stalks.  At  an 
advanced  stage  of  fructification  (September  14th),  both  the  absolute 
and  relative  quantities  of  oxalic  acid  had  diminished,  the  absolute 
quantity  being  greatest  in  the  flowers,  whereas  the  relative  propor- 
tion was  greatest  in  the  leaves.  The  relative  proportion  of  insoluble 
oxalates  had  generally  increased,  but  in  the  roots  the  proportion  of 
soluble  oxalates  had  become  somewhat  high,  a  fact  which  indicates 
that  towards  the  end  of  vegetation  the  root  absorbs  little  or  nothing 
from  the  soil. 
Mesembrianthemum  crystallinum. — Hie  seed  does  not  contain  oxalic 
acid.  In  the  early  stage  of  growth  (June  9th),  a  considerable  quantity 
of  oxalic  acid  is  formed,  a  part  being  in  the  soluble  form.  Alkaline 
salts  are  abundant  and  the  juice  is  neutral.  As  growth  proceeds 
(July  8th),  the  juice  becomes  acid  and  the  soluble  oxalates  predomi- 
nate, the  greatest  proportion  being  found  in  the  leaves.  At  a  later 
stage,  when  flowers  begin  to  open  (September  25th),  the  juice  is 
neutral  in  the  root,  but  is  acid  in  the  stalks  and  especially  in  the 
leaves. — Jour.  Chem.  Soc,  1886,  p.  734;  Compt.  rend.,  cii. 
