ASceXV,Pmr3m'}       The  Pollen  of  Poison  Sumach.  549 
of  a  few  drops  of  an  alcoholic  solution  of  potassium  hydroxide  to 
the  pollen  grains  on  the  slide  produced  no  change  of  color,  i.e.,  by 
microchemical  tests  the  pollen  appeared  to  contain  no  poisonous 
resin.  A  small  quantity  of  the  pollen  was  then  macerated  for  several 
hours  with  95  per  cent,  alcohol,  the  mixture  filtered  and  the  solution 
allowed  to  evaporate  spontaneously  to  small  volume.  A  portion  of 
the  filtrate  gave  no  black  color  or  precipitate  when  treated  with  an 
alcoholic  solution  of  potassium  hydroxide.  Another  portion  of  the 
filtrate  was  allowed  to  evaporate  spontaneously  almost  to  dryness 
and  a  drop  of  the  residue  tested  for  poisonous  properties,  according 
to  the  physiological  method  (slightly  modified)  of  Tschirch  and 
Stevens  9 : 
This  consists  in  thoroughly  rubbing  a  drop  of  the  suspected  liquid  into 
the  integument  of  the  forearm  by  means  of  a  glass  rod,  thus  covering  a  circu- 
lar area  about  1  cm.  in  diameter.  After  thirty  minutes  the  part  treated 
is  washed  with  ether,  then  with  alcohol,  and  lastly  with  soap  and  water.  If 
the  substance  were  poisonous  the  area  treated  will  exhibit  a  noticeable  redness 
and  perhaps  slight  itching  after  twenty-four  to  thirty-six  hours.  If  a  negative 
result  be  obtained  the  experiment  is  repeated  with  the  difference  that  the 
test  material  is  allowed  to  remain  upon  the  arm  for  from  one  to  two  hours. 
In  doubtful  cases  a  third  experiment  continuing  through  twenty-four  hours 
should  be  carried  out. 
When  tested  by  the  above  method  upon  four  individuals  the  alco- 
holic extract  from  the  pollen  of  Rhus  vernix  showed  absolutely  no 
poisonous  properties.  Although  these  tests,  perhaps,  should  not 
be  considered  as  absolutely  proving  the  innocuousness  of  the  pollen 
of  poison  sumach  under  all  conditions  they  furnish  strongly  pre- 
sumptive evidence  in  that  direction.  The  evidence  that  rhus  poison- 
ing may  be  wind-borne  is  materially  weakened  by  the  results  and  the 
theory  that  poisoning  can  take  place  only  by  contact  with  the  plant 
receives  additional  support. 
9 Tschirch  and  Stevens:  Arch.  Pharm.,  243,  504  (1905)  ;  also  Am.  Jour. 
Pharm.,  78,  63  (1906). 
