70 
ON  THE  DESTRUCTION  0¥  NOXIOUS  INSECTS. 
It  was  not  till  1856,  and  after  many  efforts,  that  we  could 
procure  some  good  seeds  of  the  ^Pyrethrum  of  the  Caucasus.  We 
were  then  able  to  extend  our  researches  as  to  the  culture  of  the 
plant.  We  had  to  proceed  cautiously  in  determining  the  soil 
best  adapted  to  it,  to  find  out  the  best  exposure,  and  to  discover 
the  care  necessary  to  be  bestowed  on  it.  The  first  sown,  on  Sep- 
tember 15,  1856,  produced  only  a  few  shoots.  A  great  point 
was  to  ascertain  whether  the  plant  was  an  annual  or  perennial. 
In  order  to  determine  this,  several  of  the  procured  plants  passed 
through  the  winter  of  1856-57,  and  sustained  from  8  to  12  de- 
grees of  cold  without  appearing  to  suffer. 
The  seeds  gathered  from  this  first  culture  were  sown  in  Feb- 
ruary, 1858.  In  May,  we  communicated  our  experiments,  and 
the  success  that  had  crowned  them,  to  Messrs.  Decaisne,  Neu- 
mann, and  Pepin.  These  gentlemen  then  examined  the  plant 
botanically,  and  their  opinions  are  as  follows  : — (Here  follows  a 
botanical  description  of  the  genus  Pyrethrum,  and  of  the  par- 
ticular plant  just  referred  to,  from  which  it  appears  that  the 
present  species  has  not  hitherto  been  described;  hence  M. 
Duchartre  has  named  it  Pyrethrum  Willemoti. 
Culture  and  Gathering  .—The  Pyrethrum,  though  a  native  of 
the  Caucasus,  where  it  grows  abundantly  and  at  a  slight  eleva- 
tion above  the  level  of  the  sea,  under  a  latitude  warmer  than 
that  of  Paris,  succeeds  very  well  on  good  soil  in  France.  It  is 
very  hardy,  and  can  sustain  without  hazard  the  severe  winter 
there.  A  few  years'  experience  has  taught  the  writer  that  it  is 
little  sensible  to  cold,  and  that  it  needs  no  shelter  during  the 
winter.  It  has  been  asserted  that  the  kindred  species  which  also 
grow  in  the  Caucasus  have  rather  suffered  than  benefited  by  the 
shelter  given  to  them.  The  soil  best  adapted  to  the  culture  of 
the  plant  is  a  pure  earth  somewhat  siliceous  and  dry.  Moisture 
and  the  presence  of  dung  is  injurious,  the  plant  being  extreme- 
ly sensitive  to  a  mass  of  water,  and  would  in  such  case  immedi- 
ately perish.  A  southern  aspect  is  the  most  favorable.  The 
best  time  for  putting  the  seed  in  the  ground  is  from  March  to 
April.  It  can  be  done  even  in  the  month  of  February  if  the 
weather  will  permit  it.  After  the  soil  has  been  prepared  and 
the  seeds  are  sown,  they  are  covered  by  a  stratum  of  soil  mixed 
with  some  vegetable  mould,  and  the  roller  is  slightly  applied  to 
