Am.  Tour.  Pharm 
May,  1879. 
Insect  Powder. 
2  43 
larger  than  those  in  the  accompanying  book  could  be  made  from  this 
pith.2 
The  pith  of  the  Aeschynomene  paludosa  (asp  era),  which  somewhat 
resembles  that  of  the  Aralia  papyr'ifera,  is  used  in  the  East  Indies  for 
making  floats,  light  hats,  etc.;  and  still  another  plant,  the  Sccevola  taccada, 
which  furnishes  a  pith  having  an  almost  identical  appearance,  even  under 
the  microscope,  with  the  rice  paper  pith,  is  also  employed  in  the  Malay 
Archipelago, for  making  artificial  flowers  and  small  figures.  It  is  distin- 
guished, however,  from  the  A.  papyrifera  by  the  smaller  size  of  its  cyl- 
inders, which  never  exceed  T7^  of  an  inch  in  diameter,  and  also  by  the  fact 
that  the  cylinder  of  pith  becomes  more  slender  as  the  stem  ages  and 
thickens.  Very  truly  yours, 
F.  V.  Greene,  M.D. 
INSECT  POWDER. 
By  William  Saunders. 
Reprint  from  the  Canadian  Entomologist ,  March.    Communicated  by  the  author. 
The  insect  powders  of  commerce  are  the  powdered  flowers  of  dif- 
ferent species  of  Pyrethrum.  Those  of  Pyrethrum  carneum  and  roseum 
were  introduced  some  thirty  years  ago  under  the  name  of  Persian  Insect 
Powder,  and  subsequently  those  of  Pyrethrum  cinerariafolium,  a  native 
•of  Dalmatia,  Austria,  as  Dalmatian  Insect  Powder.  Both  the  Persian 
and  Dalmatian  powders  are  good  insecticides,  but  the  latter  is  much  the 
more  energetic  in  its  action  and  hence  commands  a  higher  price ; 
indeed,  it  is  so  much  preferred  that  it  is  gradually  driving  the  so-called 
Persian  powder  out  of  the  market.  The  fact  of  the  flowers  of  P. 
roseum  being  less  active  than  those  of  P.  cinerariafolium,  has  been 
accounted  for  on  the  ground  that  the  single  flowers  are  much  more  pow- 
erful than  the  double  ones,  and  that  the  double  flowers  occur  in  P.  roseum 
in  much  larger  proportion  than  in  the  other  species.  The  flowers, 
either  whole  or  powdered,  preserve  their  activity  for  a  long  period.  A 
recent  European  experimenter  states  that  he  could  not  perceive  any 
particular  loss  of  activity  in  samples  which  had  been  kept  for  six  years. 
The  fresh  (undried)  flowers  act  very  slowly  as  compared  with  the  same 
dried  and  powdered,  and  the  plant  itself  powdered  is  quite  inactive.  It 
2  It  is  stated  that  the  parings  of  the  pith,  or  perhaps  of  the  root,  are  employed  in 
China,  in  the  form  of  infusion,  for  their  supposed  diuretic  properties. 
