Am.  Jour.  Pharm.  \ 
April,  19 1 9.  > 
Digitalis  Purpurea. 
217 
each  pot  and  harvested  after  six  months.  The  moisture  was  main- 
tained at  the  physical  optimum  of  the  soil.  After  harvesting,  the 
digitalis  leaves  were  dried  and  the  alkaloid  determinations  made. 
TABLE  IV. 
Showing  the  Effect  of  Manganese  Sulphate  and  Ferrous  Sulphate, 
Applied  to  a  Clay  Loam  Soil,  upon  the  Growth  and  Activity 
of  Digitalis. 
Pot  No. 
Treatment  Lbs.  per  Acre  of 
2,000,000  Lbs. 
Weight  of  Dry 
Material  in  Gms. 
Average  Weight 
in  Gms. 
Activity,  Per 
Cent. 
701 
No  treatment  
6-5 
702 
5-o 
6.1 
83 
703 

6.7 
704 
75  lbs.  M11SO45H2O  
7.0 
705 
8.0 
7.0 
76 
706 
5-9 
707 
i$o    '[  "   
7.2 
708 
6-5 
6V6 
100 
709 
6.2 
710 
75    "  FeS043H20  
711 
6.2 
6-5 
90 
712 
.-7 
713 
150    "  ^   
6-5 
714 
6.0 
6.1 
90 
715 
The  results  of  the  experiment  above  show  that  neither  applica- 
tion of  manganese  or  iron  sulphate  were  effective  in  increasing  the 
yield  of  digitalis  in  this  soil,  as  the  results  are  all  within  experimental 
error.  From  this,  we  would  conclude  that  this  soil  either  was  suffi- 
ciently supplied  with  manganese  and  iron  for  the  needs  of  digitalis, 
that  the  absorptive  and  adsorptive  effects  of  this  soil  were  so  great 
that  such  amounts  as  were  supplied  were  taken  from  the  field  of 
.activity  when  they  could  be  utilized  by  the  plant,  or  that  these  salts 
were  not  essential  for  digitalis.  There  was  a  considerable  varia- 
tion in  the  activity  of  the  samples  of  digitalis  harvested  from  the 
pots  which  received  the  various  treatments  of  the  salts.  This  dif- 
ference in  activity  is  most  marked  between  the  samples  receiving 
no  treatment  and  those  using  150  lbs.  MnS045H20.  Applying  this 
amount  of  MnS045H,0  was  effective  in  increasing  the  activity  17 
per  cent,  over  that  of  the  control.  In  the  case  of  the  determination 
receiving  iron,  there  is  an  indication  of  increase  in  activity  but  this 
may  be  almost  within  experimental  error. 
