REMARKS  ON  DIALYSIS. 
317 
and  more  recently  he  has  demonstrated  by  its  means  the  pres- 
ence of  alloxan  in  an  animal  secretion.  (Pharm.  Jour.  528, 
April,  1862.) 
Mr.  Buchner  has  shown  (ibid,  572)  that  when  a  thick  viscous 
mucilage  of  marshmallow  root  is  put  into  the  dialyser,  over  dis- 
tilled water,  after  two  days  the  whole  of  the  asparagin  of  the  root 
is  in  the  first  diffusate,  and  may  be  obtained  in  fine  crystals 
by  simple  evaporation. 
2d.  Mr.  Redwood  suggests  that  dialysis  offers  the  means  of 
producing  a  new  class  of  medicines,  containing  the  active  prin- 
ciple of  plants,  partially  purified,  and  in  the  state  of  combina- 
tion in  which  they  exist  in  nature,  and  he  is  now  engaged  in  ap- 
plying the  principle  to  opium  and  aloes  in  this  view.  The  field 
opening  in  this  direction  is  probably  rich  in  future  discovery,  and 
merits  the  attention  of  investigators.  The  main  difficulty  is 
the  very  dilute  condition  of  the  solution  and  the  slowness  of  the 
operation,  and  consequent  tendency  to  spoil  or  ferment ;  but  it 
may  prove,  owing  to  ferments  being  colloidal  matter,  that  the 
diffusates  may  not  be  liable  to  change  to  a  degree  that  will 
embarrass  the  operation. 
3d.  It  affords  an  elegant  means  of  separating  crystalline 
poisons,  like  arsenious  acid,  tartar  emetic,  strychnia,  morphia, 
etc.,  from  the  crude  colloidal  contents  of  the  stomach  and  in- 
testines, so  that  they  maybe  at  once  detected  unclogged  by  inert 
matter,  and  Mr.  Redwood  has  "  already  obtained  these  sub- 
stances by  dialysis  from  the  stomach,  the  flesh  and  the  blood 
of  animals  that  have  been  poisoned,  distilled  water  alone  being 
used  for  their  extraction."  The  perfect  simplicity  of  this 
method,  uncomplicated  by  chemical  agents  liable  to  contain 
these  poisons,  will  add  greatly  to  the  force  of  medico-legal  testi- 
mony in  future  prosecutions. 
4th.  Dialysis,  also,  says  Mr.  Redwood,  will  enable  us  to  ex- 
plain satisfactorily  many  physiological  and  geological  phenome- 
na which  have  hitherto  been  involved  in  much  obscurity.  The 
stomach  of  an  animal  is  a  dialysing  apparatus  ;  in  which  the 
soluble  food  is  dialysed,  and  the  insoluble  food  digested  under 
the  influence  of  crystalloids  supplied  through  the  coats  of  the 
stomach  by  diffusion,  an  action  closely  resembling  that  which 
occurs  when  hydrated  basic  chlorides  of  colloidal  oxides,  like  per- 
