548  The  Pollen  of  Poison  Sumach.  {^Jml^ioit 
and  otherwise  behaves  like  certain  phenolic  compounds.  The  toxic 
resin  exists  in  the  plant  in  the  form  of  an  emulsion  which  readily 
blackens  with  the  alkali  hydroxides.  So  delicate  is  this  reaction  that 
minute  amounts  of  the  substance  may  be  detected  by  the  microscope 
if  the  plant  tissues  be  mounted  in  an  alcoholic  solution  of  potassium 
hydroxide. 
The  author  has  long  been  skeptical  concerning  the  poisonous 
properties  of  the  pollen  of  these  plants.  Several  years  since  he  was 
informed  by  Professor  A.  B.  Stevens  that  he  (Stevens)  had  made 
some  attempts  to  isolate  the  poisonous  oil  from  the  pollen  of  Rhus 
vernix  but  without  success.  The  experiments  were  few  and  were 
not  published  although  attention  7  has  already  been  called  to  them 
in  print. 
During  the  past  summer  the  author  collected  some  of  the  pollen 
from  the  flowers  of  Rhus  vernix  L.  growing  in  northern  Indiana. 
Physiological  and  micro-chemical  tests  with  this  demonstrated  that 
it  contained  no  poisonous  constituent. 
On  three  occasions  8  during  an  interval  of  two  weeks  during  the 
1913  flowering  season  of  poison  sumach  attempts  were  made  by  the 
method  given  below  to  procure  pollen  from  numerous  male  plants: 
The  apparatus  consisted  of  a  two-inch  funnel,  a  four-inch  funnel,  a 
500  c.c.  suction  flask,  a  bicycle  compression  pump  and  gas  tubing.  The  smaller 
funnel  was  attached  to  the  pump  by  means  of  the  gas  tubing  while  the  larger 
one  was  fitted  into  the  mouth  of  the  suction  flask  by  means  of  a  perforated 
cork  stopper.  The  outlet  tube  of  the  suction  flask  acted  merely  as  an  escape 
for  air.  The  inner  surface  of  the  larger  funnel  and  the  interior  of  the  suction 
flask  were  moistened  with  75  per  cent,  alcohol.  During  the  operation  the 
smaller  funnel  was  held  near  a  panicle  and  by  means  of  the  pump  a  strong 
current  of  air  was  blown  for  some  minutes  upon  it  and  into  the  mouth  of 
the  larger  funnel  which  was  held  upon  the  opposite  side.  By  this  means 
some  pollen  was  collected  but  the  quantity  was  much  less  than  desired.  Bet- 
ter success  was  attained  by  jarring  the  flowering  stems  while  holding  the 
larger  funnel  (and  flask)  directly  below. 
Some  of  the  pollen  which  had  been  disengaged  from  the  anthers 
of  the  flowers  by  shaking  the  flower  stems,  was  placed  on  a  slide 
and  examined  with  the  microscope.  When  dry  the  pollen  is  in  the 
form  of  orange-yellow,  ellipsoidal  grains.  If  moistened  with  alcohol 
or  water  the  grains  swell  and  assume  a  globular  shape.   The  addition 
7  P harm.  J  our.,  83,  562  (1909). 
8  The  author  is  indebted  to  Prof.  A.  H.  Clark  of  the  University  of  Illinois 
School  of  Pharmacy  for  aid  in  collecting  the  pollen. 
