ON  THE  STRUCTURE  OF  THE  STARCH  GRANULE.  137 
If  a  little  boiling  water  were  poured  on  to  starch,  and  it  were  then  ex- 
amined under  the  microscope,  an  abundance  of  empty  collapsed  cells  would 
be  observed ;  and  if  this  aqueous  solution  of  starch  were  to  be  largely  di- 
luted with  water  they  would  all  gradually  fall  to  the  bottom  of  the  vessel. 
So  little  was  known  of  the  mode  of  growth  of  the  starch  cellule  that  it 
was  impossible  to  say  at  present  how  the  increment  takes  place.  It  may 
be  uniformly,  or  it  may  be  periodic,  the  difference  between  night  and  day 
possibly  being  sufficient  to  account  for  the  difference  in  density  of  the  lay- 
ers ;  that  is  to  say,  supposing  the  markings  to  indicate  concentric  layers — 
just  as  the  seasons  appear  to  affect  the  density  of  the  annular  rings  in  the 
stems  of  trees.  With  regard  to  the  direction  of  the  fissure  on  the  burst- 
ing of  the  granule,  longitudinally  would  be  the  natural  direction  in  a  body 
constituted  of  concentric  layers  ;  at  least,  it  was  very  doubtful  if  the  con- 
centric layers  would  offer  any  impediment  to  such  a  mode  of  splitting. 
From  what  is  observed  in  reference  to  exogenous  stems,  one  would  infer 
that  there  would  be  a  greater  facility  for  rupture  in  that  direction.  Wood 
splits  readily  in  the  direction  of  its  axis — that  is  longitudinally,  not  at  all 
transversely,  or  at  right  angles  to  it,  and  in  many  instances  not  readily  in 
the  direction  of  the  annulations,  or  perpendicularly  to  the  medullary  rays, 
and  in  some  of  the  coniferae  this  tendency  is  extensively  rendered  available 
in  the  production  of  laths  for  ceiling  and  roofing  purposes. 
Having  seen  Mr.  Field's  paper  before  it  was  read,  he  had  tried  the  ex- 
periment referred  to  in  it,  but  the  result  had  not  satisfied  him  that  the  ap- 
pearance observed  was  due  to  the  rupture  of  the  granules.  He  was  rather 
disposed  to  refer  it  to  a  shrinking  of  the  granule  and  consequent  puckering 
of  the  enveloping  membrane.  His  observations,  however,  had  been  some- 
what hastily  made,  so  that  he  could  not  give  a  decided  opinion.  He  thought 
that  a  further  investigation  of  the  subject  was  required,  and  that  many 
more  observations  must  be  made  before  either  of  the  theories  which  had 
been  propounded  could  be  considered  as  established. 
Mr.  Giles  said,  as  the  Chairman  seemed  to  differ  from  the  author  of  the 
paper  as  to  the  cause  of  the  appearance  presented  by  starch  granules  when 
immersed  in  solution  of  glycerine,  the  latter  describing  the  action  as  that 
of  a  swelling  of  the  granule  and  a  bursting  of  its  envelope,  while  the  for- 
mer considered  that  a  reverse  action  took  place,  he  thought  it  desirable 
that  some  experiments  should  be  made  to  determine  the  mode  of  action  of 
aqueous  solution  of  glycerine  and  of  starch  on  membrane.  If  it  should 
be  found  that,  in  accordance  with  the  usual  phenomena  of  endosmose  and 
exosmose,  a  thin  solution  of  glycerine  permeated  membrane  more  quickly 
than  the  thick  gelatinous  contents  of  the  starch  granule,  this  would  afford 
a  strong  argument  in  favor  of  Mr.  Field's  opinion. 
Dr.  Edwards  thought  the  question  a  very  difficult  one  to  decide,  and 
therefore  one  upon  which  much  difference  of  opinion  would  probably  con- 
tinue to  exist.    The  Chairman  appeared  to  meet  Mr*  Field  half-way,  for 
