and  their  Adulteration. 
709 
suitable  seeds  for  the  purposes  of  adulteration.  It  would  seem 
difficult  to  understand  why  in  this  case  seed-collectors  should 
gather  the  seeds  of  a totally  different-looking  and  worthless 
grass,  when  the  same  labour  would  secure  the  seeds  of  the  valu- 
able yellow  oat-grass.  The  two  grasses  do  not  naturally  grow 
together.  The  seeds  are  collected  separately,  and  are  sold,  each 
pure  of  its  kind,  and  both  as  the  seeds  of  Avena  Jlavescens. 
Fig.  6. — Wavy  Mountain  Hair  Grass,  Aira  Jlexuosa,  Linn.  Ten  times  th^  natural  size,  a,  Inner 
surface  of  the  seed,  showing  the  pedicel  of  the  next  seed,  with  a pencil  of  hairs  on  either  side  ; 
b,  side  view,  in  which  the  inner  pale  cannot  be  seen;  c,  back  view,  showing  the  place  ol 
attachment  of  the  hygrometric  awn,  and  the  entire  apex  of  the  outer  pale. 
When  one  examines  a little  more  closely  into  the  relations  ol 
the  two  seeds,  it  is  however  easy  to  discover  the  reasons  that 
induce  unprincipled  merchants  to  substitute  the  one  for  the 
other.  Aira  flexuosa  seeds  abundantly,  and  its  seeds  are  three 
times  heavier  than  the  seeds  of  Avena  Jlavescens,  so  that,  other 
things  being  equal,  the  labour  of  collecting  3 cwt.  of  the  one 
grass  would  secure  only  1 cwt.  of  the  other.  But  other  things 
are  not  equal,  for  the  Aira , where  its  seeds  are  gathered,  grows  in 
