DATURA  STRAMONIUM  AND  D.  TATULA. 
341 
DATURA  STRAMONIUM  AND  D.  TATULA. 
The  following  is  given  in  connection  with  the  spontaneous  re- 
turn of  hybrid  plants  to  their  parental  forms,  and  is  also  interest- 
ing from  the  fact  that  both  are  now  in  use  for  medicinal  purposes. 
Naudin  maintains  that  hybrid  plants,  however  constant  at  first 
tend  in  subsequent  generations  to  a  separation  of  the  two  specific 
elements,  which  are,  as  he  expresses  it,  rather  intermixed  than 
truly  combined,  so  that  they  would  at  length  resolve  themselves 
into  the  two  parental  types,  or  by  failure  on  one  side  return  to 
the  one  or  the  other.  In  the  "  Flore  des  Serres  "  for  July,  1864, 
he  gives  the  results  of  his  experiments  upon  our  common  sorts  of 
thorn-apple,  Datura  Stramonium  and  D.  Tatula.  These  have 
more  commonly  been  taken  for  varieties  of  one  species ;  but  their 
specific  distinction  has  been  maintained,  especially  of  late,  by 
various  arguments.  According  to  Naudin,  they  are  truly  distinct 
species  which  do  not  sensibly  vary.  One  always  exhibits  green 
stems  and  pure  white  flowers ;  the  other  dark  purple  stems  and 
violet-tinged  flowers.  These  two  thorn-apples  M.  Naudin  crossed 
in  1855,  and  obtained  one  hundred  or  more  hybrids,  both  Tatula 
stramonium  and  Stramonio  tatula,  both  just  alike,  and  exactly 
intermediate  between  the  two  species  in  the  coloration  of  the  stem 
and  flowers.  They  had,  however,  the  peculiarity  of  a  gigantic 
size,  attaining  at  least  twice  the  size  of  their  parents,  and  a  ten- 
dency to  sterility,  which  was  manifested  in  the  failure  of  all  the 
flower-buds  which  were  produced  at  the  first  forking  of  the  stems. 
The  later  flower-buds  opened,  however,  and  were  perfectly  fertile, 
the  pods  being  as  large  and  as  full  of  good  seeds  as  those  of  either 
parent.  In  1861  the  seeds  of  Stramonio  tatula  were  sown,  and 
produced  a  second  generation  like  the  first.  Seeds  of  this  crop 
were  sown  in  1862,  and  twenty-two  seedlings  were  preserved  for 
experiment.  Nine  individuals  returned  as  completely  to  I).  Ta- 
tula, and  five  did  to  D.  stramonium.  Two  others  seemed  to  be 
D.  Tatula,  and  were  equally  reduced  in,  and  fertile  from  the  first 
forks,  but  they  still  showed  in  their  paler  coloring  a  trace  of  the 
other  ancestor.  The  remaining  six  of  the  twenty-two  showed 
somewhat  more  of  it,  both  in  color  and  in  the  tallness  and  late- 
ness of  fructification.    "  Here,  then,"  says  Naudin, <;  is  a  hybrid 
