2l6 
Digitalis  Purpurea. 
Am.  Jour.  Pharm. 
April,  1919. 
of  digitalis.  Phosphorus  and  nitrogen  seemed  to  be  the  elements 
which  the  digitalis  plants  needed  most.  In  the  determinations  where 
no  phosphorus  was  supplied,  the  growth  of  digitalis  was  about  the 
same  as  the  controls.  This  would  indicate  that  the  other  fertilizers 
supplied  were  not  effective  in  increasing  the  plant  growth  until  some 
available  phosphorus  was  furnished.  There  seemed  to  be  sufficient 
potash  and  lime  in  this  sand  to  fulfill  the  needs  of  digtalis,  as  the 
growth  of  digitalis  in  the  determinations  where  these  were  absent: 
430,  431/432  and  436,  437,  438,  respectively,  was  as  large  as  that  in 
the  determination  receiving  a  complete  fertilizer. 
Effect  of  Certain  Inorganic  Salts  upon  the  Growth  and 
Alkaloid  Content  of  Digitalis. 
Certain  inorganic  salts  stimulate  the  growth  of  some  agricul- 
tural plants.  Salts  of  manganese  have  this  property.  Boname  (4) 
and  others  have  shown  that  manganese  in  small  amounts  occurs  in 
various  soils  and  plants.  Rogers  and  Newcomb  (13)  state  that 
manganese  appears  to  be  a  constant  constituent  of  digitalis  leaves, 
but  the  amount  varies  with  the  source  from  which  the  samples  are 
obtained.  Alpers  (2)  states  that  digitalis  is  generally  found  grow- 
ing in  soil  which  contains  iron  and  manganese.  It  is  true  that  all 
soils  contain  a  certain  amount  of  iron  and  according  to  Boname  (4), 
soils  contain  a  certain  amount  of  MnOa.  According  to  Gehe  (2), 
it  is  due  to  the  lack  of  these  elements  (Mn  and  Fe)  that  digitalis 
does  not  occur  in  Switzerland. 
To  determine  if  salts  of  manganese  or  iron  affected  either  the 
growth  or  the  alkaloid  content  of  digitalis  when  grown  in  soil,  a  pot 
experiment  was  carried  out  under  controlled  conditions.  Into  each 
of  fifteen  5  inch  pots,  1,000  Gm.  of  a  clay  loam  soil  (the  same  as 
used  in  the  above  pot  experiment)  were  weighed.  The  same  amount 
of  a  complete  fertilizer  of  800  lbs.  Ca(H2P04)22H20,  400  lbs. 
K2S04,  600  lbs.  NaN03,  1,000  lbs.  CaC03  and  100  lbs.  MgS04  per 
acre  of  2,000,000  lbs.,  was  added  to  each  pot.  To  six  pots,  man- 
ganese sulphate  (MnS04,  5H0O)  in  amounts  usually  applied  in  field 
experiments  with  agricultural  crops,  was  added ;  to  six  others,  fer- 
rous sulphate  (FeS04,  3H20),  and  the  other  three  determinations 
were  used  as  controls  receiving  neither  salts  of  Mn  or  Fe.  Digitalis 
seed  was  planted  in  these  pots  on  May  28,  and  after  the  plants  were 
about  2  inches  high,  they  were  thinned  out  to  an  equal  number  in 
