146     ON  THE  MILKY  JUICE  OF  LACTUCA  ELONGATA,  MUHL. 
tucarium  might  be  most  advantageously  obtained,  the  milky 
juice  of  this  plant  is  of  a  flat  and  sweetish  taste,  without  bitter- 
ness, contains  much  mannite,  but  no  bitter  principle,  and  is  des- 
titute of  narcotic  properties.  (Ann  de  Therap.,  1843,  p.  18.) 
The  probability  is  that  it  is  nearly  or  quite  inert.  Therefore, 
though  formerly  holding  a  place  in  our  national  Pharmacopoeia, 
it  has  been  discarded." 
The  subject  has  interested  me  for  some  years,  since  I  had 
often  observed,  when  out  on  botanical  excursions,  that  the  leaves 
of  the  different  varieties  of  our  Lactuea  possess  a  strongly  and 
lastingly  bitter  taste. 
After  the  last  annual  meeting,  during  the  fine  days  of  Septem- 
ber, 1867,  I  commenced  the  collection  of  the  milky  juice  from 
vigorous  plants  growing  in  a  damp  thicket.  Most  of  the  plants 
had  attained  the  height  of  six  to  eight  feet,  with  the  leaves  on 
the  upper  half  of  the  stem  green  and  juicy,  and  bearing  flowers 
and  ripe  fruits.  Oblique  incisions  were  made  on  various  places 
of  the  stem.  The  exuding  juice,  in  a  few  minutes,  lost  its  fluidi- 
ty and  became  gelatinous;  though  still  soft,  it  possessed  sufii- 
cient  firmness  and  tenacity  to  be  scraped  off"  with  the  blade  of  a 
knife.  To  increase  the  quantity,  the  leaves  were  pulled  off  at 
the  stem,  and  thus  a  portion  of  the  bark  was  usually  removed. 
The  wound  almost  instantly  became  covered  with  the  juice,  which, 
however,  likewise  soon  ceased  to  flow  in  consequence  of  gela- 
tinizing ;  when  this  soft  mass  was  now  removed  the  juice  did  not 
again  commence  to  flow,  or  to  the  utmost  only  a  minute  quantity 
was  obtained  in  addition. 
In  consequence  of  this  rapid  congelation,  I  was  unable  to  unite 
the  different  tears  so  as  to  form  a  uniform  'mass  similar  to  the 
European  lactucarium.  On  drying,  at  ordinary  temperature, 
these  tears  shrunk  considerably  and  very  irregularly,  without, 
however,  coalescing  into  a  uniform  mass.  The  recent  milky 
juice  collected,  as  stated  before,  in  a  gelatinous  condition  yielded 
22-13,  24  and  32-23  per  cent,  dry  residue. 
The  lactucarium  thus  obtained  is  in  irregular  pieces,  deeply 
corrugate  and  with  the  ridges  rather  acute ;  it  has  a  grey  brown- 
ish color,  persistently  bitter  taste  and  a  heavy,  nauseous,  nar- 
cotic odor,  milder  than  and  distinct  from,  but  at  the  same 
