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ON  THE  STRUCTURE  OF  THE  STARCH  GRANULE. 
very  pparing  distensibility  ;  and  that  the  superficial  markings  are 
simply  minute  folds  in  the  membrane,  probably  caused  by  some 
contraction  that  the  granule  undergoes  in  passing  from  the  fresh 
state,  as  it  exists  in  the  plant,  to  the  dry  form. 
2,  Southward  Terrace,  Highgate, 
The  Chairman  said,  that  Mr.  Field's  experiments  tended  to  confirm  the 
views  which  had  been  entertained  by  other  observers  ;  such,  for  instance, 
as  Mr.  Geo.  Busk,  who,  in  December,  1852,  before  the  Microscopical  So- 
ciety, read  a  clever  and  interesting  paper  "  On  the  Structure  of  the  Starch 
Granule."  His  reasons  carried  great  weight,  one  of  the  strongest  argu- 
ments being  founded  on  the  action  of  heat  and  other  agents  which  cause 
the  granule  to  swell,  and  before  bursting,  the  concentric  lines  were  found 
to  disappear  ;  thus  tending  to  prove  that  the  lines  are  on  the  surface.  Still 
he  (Mr.  Deane)  had  not  been  able  to  satisfy  his  mind  that  such  views  were 
altogether  correct.  He  rather  inclined  to  those  of  Schleiden  and  others, 
and  more  particularly  those  of  the  late  Dr.  Pereira,  who,  when  preparing 
his  last  edition  of  the  Elements  of  Materia  Medica,  devoted  much  time  to 
this  difficult  question.  Dr.  Pereira  considered  the  granule  to  consist  of 
concentric  layers,  inclosed  in  a  smooth,  tough  membrane  or  cell.  The  mo- 
dels on  the  tables,  designed  by  him,  and  made  expressly  to  illustrate  his 
lectures,  would  in  some  degree  explain  his  views.  Mr.  Field  considered 
the  concentric  markings  to  be  external  corrugations  ;  and  Mr.  Busk  and 
others,  that  these  corrugations  are  on  one  side  only.  Now  these  markings 
were  found  to  exist  equally  in  starch  fresh  from  the  tuber  as  in  that  which 
had  been  dried,  and  therefore  they  could  not  be  the  effect  of  any  shrinking 
by  loss  of  moisture.  In  the  case  of  Yam  starch,  which  consists  of  flat 
grains,  it  would  be  observed,  on  looking  on  its  flat  side,  that  the  rings  fol- 
lowed the  broad  outline,  and  on  looking  on  the  edge  that  they  equally  fol- 
lowed the  narrow  outline,  results  similar  to  what  would  be  obtained  on 
viewing  in  the  same  way  a  nest  of  flat  glass  shades.  If  a  little  Yam  starch 
were  placed  in  water  between  two  pieces  of  glass  under  the  microscope, 
most  of  the  grains  would  appear  on  their  flat  sides,  but  some  few  would  be 
on  edge,  or  if  not,  they  might  be  made  to  turn  over,  so  as  to  show  their 
edges,  by  giving  a  slight  lateral  movement  to  the  covering  glass,  when  they 
may  be  readily  observed  in  every  position.  This  peculiarity  of  marking, 
lie  thought,  was  not  much  like  mere  external  corrugations,  but  more  like 
the  effect  produced  by  superposed  layers,  and  he  believed  it  was  this  starch, 
so  well  adapted  from  its  form  to  demonstrate  the  theory,  that  confirmed 
Dr.  Pereira  in  the  opinion  he  entertained.  It  did  not  follow  that  because 
there  were  concentric  layers  of  matter  there  should  be  concentric  mem- 
branes enveloping  those  layers,  any  more  than  that  there  should  be  a  tough 
bark  investing  every  annulation  in  an  exogenous  stem.  That  there  was 
one  general  investing  membrane  or  cell  there  was  no  difficulty  in  showing. 
