509 
‘Jan.  1,  1897.]  Supplement  to  the  ''Tropical  Agriculturist'’' 
THE  NUTRITIVE  PROCESS  IN  PLANTS. 
(Prof.  J.  Reynolds  Green,  d.s.c.,  f.r.s.) 
Proteid  stores  are  not  however  confined  to 
seeds.  If  we  examine  a young  potato  we  find 
in  certain  cells,  a little  way  below  the  outer  skin 
some  regular  cubical  transparent  crystals  of  appa, 
rently  the  same  material  as  the  crystalloid  of 
the  complex  aleurone  grain. 
The  fleshy  roots  we  have  noticed  as  contain- 
ing stores  of  sugar,  also  contain  large  stores 
of  proteid  material,  which  is  held  in  the  meshes 
of  the  protoplasm  of  the  cells  in  amophous 
and  not  granular  form.  It  can  be  dissolved  out  by 
appropriate  solvents  aud  its  chemical  nature 
ascertained.  The  way  in  which  these  bodies 
reach  their  ultimate  reservoirs  is  not  quite  so 
well  known  as  is  the  case  with  starch.  The 
seat  of  construction  we  have  seen  to  be,  in  tlie 
first  case  the  cells  of  the  leaves,  the  same  cells 
most  likely  in  which  the  carbohydrate  matter 
is  formed.  But  we  have  not  yet  found  any 
enzyme  there  which  will  act  upon  them  as 
diastase  acts  upon  starch.  We  do  not  know 
what  form  of  proteid  the  leaf  con.structs.  But 
whatever  it  may  be,  and  however  it  may  be 
made  soluble,  there  is  no  doubt  that  it  leaves 
the  leaf  and  travels  down  the  vascular  bundles 
much  as  the  sugar  does,  the  form  in  which  it 
goes  being  partly  that  of  some  variety  of  pro- 
teid, and  partly  that  of  crystalline  bodies  called 
by  the  chemists  ainides,  of  which  asparagin  is 
the  most  common.  Arrived  at  the  seat  of  its 
deposition,  the  packing  away  of  it  in  the  form 
of  aleurone  grains  seems  to  be  carried  out  by 
the  protoplasm  of  the  cell,  and  not  to  be  the 
work  of  a plastid  of  any  kind.  The  mode  of 
the  formation  has  been  traced  out  in  the  seed 
of  the  lupin,  a leguminous  seed  a good  deal 
like  the  bean.  In  this  seed  they  begin  to  be 
formed  at  a very  early  period,  just  a.s  the  growth 
of  the  embryo  is  sufficiently  advanced  to  swell 
out  the  seed  coat.  The  cells  of  the  emb  -yo  at 
that  period  show  the  protoplasm  not  sufficient 
in  amount  to  fill  each  cell,  so  that  a number 
of  spaces  or  vacuoles  occur  filled  with  sap. 
Somewhere  from  the  protoplasm  small  project- 
ions of  spherical  or  ovoid  shape  may  be  noticed 
which  gradually  increase  in  size,  growing  in- 
wards into  the  protoplasm  ns  well  as  outwards 
into  the  vacuole,  till  they  can  be  seen  to  be  in 
the  form  of  grains  embedded  in  the  protoplasm, 
which  in  consequence  of  their  developement, 
a.«sumes  the  appearance  of  a coarse  net  work, 
As  this  process  continues,  the  original  grains 
growing  in  size  and  new  ones  being  constantly 
formed,  the  original  v cuole  becomes  obliterated 
and  the  cell  swollen  out  by  its  own  deposits. 
While  this  mechanical  process  is  going  on,  che- 
mical changes  also  take  place  in  the  material  depo- 
sited. The  protoplasm  forms  the  grains  originally 
at  the  e.xpense  of  the  amide  bodies  brought  down 
to  the  cell ; these  can  he  detected  in  it  at  the  time 
the  aleurone  forma’ ion  is  beginning.  .\s  the  grains 
begin  to  be  formed  they  are  not  soluble  in  10  per 
cent  or  saturated  solutions  of  common  salt.  Later 
on  they  can  be  di.=solved  by  both  of  these  fluids. 
The  deposition  of  aleurone  in  the  cells  is  thus, 
like  that  of  starch,  a process  of  secretion  carried 
out  by  the  protoplasm,  a process,  that  is,  of 
manufacture  of  the  grain  by  the  latter  out  of  less 
highly  organized  material  brought  to  it.  It  is  so 
constructed  by  the  intervention  of  the  protoplasm 
itself,  the  grain  growing  at  the  apparent  expense 
of  the  substance  of  the  latter.  There  is  no 
doubt  that  the  amorphous  deposits  of  proteids 
in  the  cells  of  fleshy  roots  and  stems  are  due 
to  a similar  process  of  secretion. 
There  is  yet  another  form  of  reserve  material 
which  i-  of  very  common  occurrence  in  many 
agricultural  plants;  this  is  oil  which  is  prominent 
in  the  seeds  of  various  families.  Specially  may 
be  mentioned  rape,  hemp  and  linseed ; in  less 
amount  we  find  it  in  many  leguminous  and  cruci- 
ferous plants.  The  mule  of  deposition  of  oil 
or  fat  is  not  much  known.  It  is  generally  found 
saturating  the  protoplasm  of  the  cell  in  which 
it  lies,  and  not  occupying  a definite  space  as 
do  aleurone  aud  starch  grains.  Whether  it  is 
secreted  from  the  substance  of  the  protoplasm, 
or  whether  the  materials  of  which  it  is  made 
are  taken  to  the  latter  in  a state  near  the 
state  of  finished  fat,  is  uncertain.  It  is  formed 
by  the  combination  of  a fatty  acid  with  glycerine. 
Both  these  bodies  can  be  formed  in  the  plant, 
but  how  they  are  finally  presented  to  us  in  the 
state  of  oil  is  still  in  need  of  elucidation.  As 
the  oil  appeal’s  in  the  cell  it  seems  to  point  to 
a process  of  breaking  down  of  the  protoplasm 
itself,  and  not  to  a direct  combination  of  the 
antecedents.  Thus  if  we  stain  cells  which  are 
forming  fat  with  osmic  acid,  which  colours  fatty 
bodies  brown  or  black,  we  see  in  the  protoplasm 
small  specks  of  fatty  matter,  which,  while  in  the 
youngest  cells  are  mere  dots,  are  in  the  older 
ones  larger,  and  can  be  recognised  as  droplets.  In 
older  ones  still  the  blackness  permeates  the  whole 
protoplasm,  indicating  that  the  latter  is  saturated 
with  the  oil,  the  droplets  having  rnn  together 
in  consequence  of  their  number  and  dimensions, 
Pat  or  oil  is  not  only  deposited  in  seeds  bub 
also  occurs  in  similar  quantity  in  the  leaves  of 
plants  belonging  to  certain  orders,  particularly 
the  Liliacete.  Drops  of  oil  may  be  seen  in  the 
cells  of  the  epidermis  of  the  leaves  of  vanilla 
of  the  coloured  floral  leaves  of  ornithogalum  ^e. 
These  cells  also  contain  curious  bodies  of  very 
irregular  shape,  lying  near  the  nucleus,  which 
have  been  thought  bj’  their  discoverer  to  be 
plastids  like  the  chloro  plastids  and  leucoplastids 
already  spoken  of.  They  are  like  them  composed 
of  a .spongy  protoplasmic  frame  work,  but 
contain  no  colouring  matter.  The  oil  is  formed 
in  the  meshes  of  these  plastids,  much  as  it  is 
formed  in  the  protoplasm  of  the  seeds  already  des- 
cribed. These  bodies  have  been  called  elaioplasts. 
Other  forms  of  stored  material  may  be  met 
with  in  plants.  Inulin  in  artichokes,  cellulose  in 
palms  and  other  plants  (to  a small  extent  in 
cereal  gr.is-es) ; curious  bodies  known  as  glucosides 
in  many  plants,  particularly  seeds  of  crucifers 
such  as  mustard  &c.  These  are  less  common 
than  the  forms  described,  and  seems  rather  to 
be  appropriate  only  to  a few  plants. 
AVhatever  m;iy  be  the  character  of  the  material 
its  meaning  is  the  same  ; it  shows  us  the  provision 
of  nature  for  the  maintenance  of  the  orcranism 
during  times  unfavourable  for  nutrition,  and  for 
the  survival  of  the  species  under  the  peculiar 
conditions  of  cessation  of  active  life  which  are 
characteristic  of  the  seed. 
(TAe  End.) 
