A™ovimb4rf loiT* }    The  Germination  of  Belladonna  Seed.  495 
minate  in  about  three  weeks  after  sowing.  The  bulk  of  the  seeds 
germinate  between  the  fourth  and  fifth  week.  After  that  the  progress 
is  slow,  a  few  per  cent,  of  the  total  appearing  every  week  for  probably 
several  months.  Figure  5  illustrates  this  lack  of  uniformity  in  germi- 
nation. 
It  has  often  been  observed  that  new  plants  will  appear  after 
the  others  sown  at  the  same  time  are  seven  to*  eight  inches  high.  In 
some  cases  this  might  be  due  to  lack  of  uniformity  in  sowing  as 
regards  character  and  condition  of  soil  and  depth  of  soil  covering 
the  seed.  This  might  be  especially  true  when  sowing  in  the  field. 
In  greenhouse  work,  however,  such  conditions  are  generally  avoided, 
and  a  different  explanation  must  be  found.  It  was  thought  that 
possibly  these  slowly  germinating  seeds  might  be  what  are  generally 
known  as  "  hard-heads,"  that  is,  seeds  with  such  heavy  outer  walls 
that  the  necessary  warmth  and  moisture  essential  to  germination  can 
penetrate  but  slowly.  It  is  well  known  that  with  such  seeds  ger- 
mination can  sometimes  be  hastened  by  treating  them  with  some 
substance  like  strong  corroding  acids  that  will  partly  disintegrate 
the  outer  covering  of  the  seed.  Such  treatment,  of  course,  is  fatal 
if  allowed  to  go  too  far. 
Miller  1  found  concentrated  sulphuric  acid  beneficial  when  applied 
for  a  period  ranging  from  five  to  fifteen  minutes,  the  ten-minute 
application  giving  by  far  the  best  results.  He  does  not  state,  however, 
the  actual  percentage  of  germination  obtained  by  means  of  the 
treatment.  T.  B.  Young  found  a  five-minute  treatment  with  concen- 
trated sulphuric  acid  very  beneficial,  but  concluded  that  a  ten- 
minute  treatment  would  be  too  long.  Here  again  data  as  to  the 
actual  percentage  of  germination  are  not  available. 
To  obtain  further  information  on  this  subject,  belladonna  seed 
was  subjected  to  sulphuric  acid  of  various  strengths  and  for  various 
periods  as  shown  in  Table  X. 
A  convenient  quantity  of  seeds  were  treated  for  the  required 
length  of  time  with  acid  of  the  desired  strength  in  a  small  beaker 
and  then  quickly  transferred  to  a  Gooch  crucible  attached  to  a  vacuum 
flask  and  rapidly  and  repeatedly  washed  with  water.  They  were 
then  dried  by  pulling  air  through  the  crucible. 
To  determinate  the  relative  germination  of  these  treated  seeds, 
1  Miller,  Fred  A.,  "  The  Propagation  of  Medical  Plants,"  Bulletin  of  the 
Torrey  Botanical  Club,  vol.  41,  No.  2,  pp.  105-136. 
