XeXVPmT-}      The  Pollen  of  Poison  Sumach.  547 
even  in  winter  time.  Generally  the  hairs  penetrate  into  the  sudoriferous  and 
sebaceous  glands  and  this  observation  is  corroborated  by  the  fact  that  those 
parts  of  the  skin  perspiring  easily  are  affected  most  frequently." 
Schwalbe  states  4  that  the  poisonous  oil  may  be  detected  in  and 
on  the  pollen  grains, 
"  Der  Bliiten-staub  enhalt  das  gif  tige  Oel  in  kleinen  Mengen ;  man  kann 
in  und  an  den  Pollen  Kornnern  das  Toxicodendrol  nachweisen." 
Von  Adelung,5  too,  inclines  to  the  opinion  that  the  pollen  of  these 
plants  contains  the  poisonous  oil.   He  says  : 
"  That  persons  are  poisoned  without  direct  contact  with  the  plant  is  too 
common  an  observation  to  be  denied.  The  explanation  is  doubtless  the 
mechanical  transportation  of  the  poison,  as  happens  when  the  pollen,  or  the 
plant  hairs,  or  other  dust  "from  the  plant  is  carried  by  air  currents.  Or, 
perhaps  as  commonly,  the  transporting  agents  are  simply  clothes  or  tools  or 
animals,  which,  after  brushing  against  the  plant,  are  able  to  transfer  the 
poison  to  susceptible  persons." 
On  the  other  hand  Rost  and  Gilg  6  have  studied  the  toxic  effects 
of  Rhus  toxicodendron  from  specimens  grown  in  the  botanical  gar- 
dens at  Dahlem  and  have  concluded  that  neither  the  hairs  nor  the 
pollen  of  that  plant  contain  any  of  the  poison..  They  obtained  the 
hairs  partly  by  blowing  a  current  of  air  across  the  detached  branches 
of  the  plant  while  confined  in  a  glass  case  and  collecting  the  dis- 
engaged particles  on  glass  plates  moistened  with  diluted  glycerol 
and  partly  by  placing  open  dishes  containing  diluted  glycerol  under 
the  standing  bushes.  Their  findings  for  the  hairs  and  pollen  of 
R.  toxicodendron  are  exactly  the  reverse  of  those  reported  by 
Schwalbe  for  R.  diversiloba.  Since  the  two  plants  are  so  similar 
botanically  and  their  physiological  effects  are  identical,  the  differ- 
ences noted  are  scarcely  to  be  explained  except  on  the  ground  of 
careless  observation  by  one  or  the  other  of  the  experimenters.  The 
studies  of  Rost  and  Gilg  were  so  carefully  carried  out  and  were, 
withal,  so  exhaustive  that  the  preponderance  of  evidence  appears  to 
lie  in  their  favor. 
It  is  known  that  the  poisonous  principle  of  the  several  species  of 
Rhus  is  an  amber-red,  non-volatile,  liquid,  resinous  substance  which 
combines  with  the  alkali  hydroxides  to  form  nigrescent  compounds 
4Muench.  med.  Woch.,  49,  1616  (1902). 
5  Arch.  Int.  Med.,  2,  148  (1913). 
6  Ber.  Pharm.  Gesellschaft,  22,  296  (1912). 
