54^  Rap  hides  the  Cause  cf  Acridity.       { AniNov.r'Sarm' 
this  turbidity  a  drop  of  the  ether  was  allowed  to  evaporate  on  a 
glass  slide.  Under  the  microscope  the  slide  was  found  to  be 
covered  with  a  mass  of  raphides.  A  portion  of  the  ether  was  run 
th  rough  a  Munktell  filter.  The  filtered  ether  was  clear,  entirely 
free  from  raphides,  and  had  also  lost  every  trace  of  its  acridity. 
The  same  operations  were  repeated  upon  the  Indian  turnip  with 
exactly  similar  results. 
These  experiments  show  conclusively,  that  the  acridity  of  the 
Indian  turnip  and  calla  is  due  to  the  raphides  of  calcium  oxalate  only. 
The  question  of  the  absence  of  acridity  in  the  other  two  plants 
still  remained  to  be  settled.  For  this  purpose  some  recent  twigs 
and  leaves  of  the  fuchsia  were  subjected  to  pressure  in  a  tincture 
press.  The  expressed  juice  was  not  limpid,  but  thick,  mucilaginous 
and  ropy.  Under  the  microscope  the  raphides  seemed  as  plentiful 
as  in  the  case  of  the  two  acrid  plants.  When  diluted  with  water 
and  shaken  with  ether,  there  was  no  visible  turbidity  in  the  super- 
natant ether,  and  when  a  drop  of  the  ether  was  allowed  to  evaporate 
on  a  glass  slide,  only  a  few  isolated  crystals  could  be  seen.  From 
this  it  will  be  seen  that  in  this  case  the  raphides  did  not  separate 
from  the  mucilaginous  juice  to  be  held  in  suspension  in  the  ether. 
A  great  deal  of  time  and  labor  were  spent  in  endeavoring  to  sepa- 
rate the  crystals  completely  from  this  insoluble  mucilage  but  without 
avail.    With  the  tradescantia  similar  results  were  obtained. 
From  these  experiments  the  absence  of  acridity  in  these  tw.a 
plants,  in  spite  of  the  abundance  of  raphides,  may  readily  be  ex- 
plained by  the  fact,  that  the  minute  crystals  are  surrounded  with 
and  embedded  in  an  insoluble  mucilage,  which  prevents  their  free 
movement  into  the  tongue  and  surface  of  the  mouth,  when  portions 
of  the  plants  are  tasted. 
The  reason  why  the  Indian  turnip  loses  its  acridity  on  being 
heated,  can  be  explained  by  the  production  of  starch  paste  from 
the  abundance  of  starch  present  in  the  bulbs.  This  starch  paste 
would  evidently  act  in  a  manner  similar  to  the  insoluble  mucilage 
of  the  other  two  plants. 
So  also  it  can  readily  be  seen  that  when  the  bulbs  of  the  Indian 
turnip  have  been  dried,  the  crystals  can  no  longer  separate  from  the 
hard  mass  which  surrounds  them,  and  consequently  can  exert  no 
irritant  action  when  the  dried  bulbs  are  placed  against  the  tongue. 
— Jour.  Amer.  Chem.  Soc,  Sptb.,  1 891,  p.  215. 
