54o 
Belladonna  and  Hyoscyamus. 
J  Am.  Jour.  Pharm. 
|   December,  1914. 
within  a  short  time  every  plant  had  produced  a  flower  stalk,  flowers, 
and  fruit.  The  plants  continued  flowering  throughout  the  early 
summer  and  then  died. 
The  results  of  these  experiments,  in  so  far  as  semi-latent 
characters  are  concerned,  may  be  summarized  in  a  very  few  lines. 
Altogether  over  twelve  hundred  plants  were  grown,  and  these  were 
subjected  to  a  number  of  varying  conditions,  with  the  result  that 
not  a  single  plant  showed  any  tendency  to  change  from  the  annual 
to  the  biennial  form  or  from  the  biennial  to  the  annual  form. 
While  these  experiments  are  probably  not  conclusive,  they  indicate 
that  pure  races  probably  exist  of  the  annual  and  biennial  forms  of 
Hyoscyamus. 
Hybridization. 
The  work  which  I  have  thus  far  done  has  not  included  any  ex- 
perimental crossing  of  the  different  species  and  varieties  of 
Hyoscyamus,  but  in  the  attempt  to  secure  pure  species  and  races 
for  later  work  some  observations  have  been  made  which  seem  worthy 
of  mention.  Throughout  the  cultivation  of  Hyoscyamus  it  has  been 
noted  that  the  amount  of  pigment  in  the  flowers  was  exceedingly 
variable.  In  Hyoscyamus  there  are  two  distinct  color  units,  which 
may  be  termed  physiologic  units.  The  first  of  these  is  represented 
by  anthocyanin,  to  which  is  due  the  dark  coloring  of  the  veins  of 
Hyoscyamus  niger,  and  the  second  is  a  yellow  element.  During  the 
past  season,  when  several  hundred  plants  of  Hyoscyamus,  grown 
from  commercial  seed  supplies,  were  under  cultivation,  I  arranged 
twenty  plants,  each  with  a  slightly  varying  amount  of  color,  in  such 
an  order  as  to  represent  at  the  one  end  a  typical  specimen  of  H.  niger 
with  the  maximum  amount  of  anthocyanin,  while  at  the  other  end 
of  the  row  a  plant  difficult,  if  not  impossible,  to  distinguish  from 
typical  H.  albus.  This  condition  appears  to  be  explained  by  the 
somewhat  extended  experiments  on  the  hybridization  of  different 
species  and  forms  of  Hyoscyamus  by  De  Vries  and  by  C.  Correns. 
From  the  results  of  these  experiments  it  is  shown  that  H.  niger  var. 
annual  readily  crosses  with  H.  albus,  and  that  the  anthocyanin  is  a 
dominant  character.  Crosses  between  H.  niger  annual  and  H.  niger 
biennial  have  also  been  made,  and  in  such  crosses  the  biennial  form 
appears  to  dominate.  The  pedigree  of  the  crosses  conforms  to  the 
laws  of  Mendel,  even  when  the  experiments  have  been  carried  into 
the  third  generation. 
