52  EFFECTS  OF  SOIL,  ETC.  ON  ACTIVE  PRINCIPLES  OF  PLANTS 
also  found  in  the  juice  extracted  from  the  leaves.  In  nearly  all 
cases  the  juices  extracted  from  the  seeds  react  much  more 
strongly  on  litmus  paper  than  the  juices  from  the  leaves  or 
stalks,  and  it  is  a  notorious  fact  that  this  acid  reaction  disap- 
pears by  drying  the  plants. 
The  following  is  the  percentage  of  active  principles  and  salts 
obtained  by  my  experiments  from  the  following  plants,  grown 
under  different  conditions  : — 
I  jPRVPS 
Seeds. 
Leaves. 
Stems,  and 
Stalks. 
Salts. 
f  4-5 
\  berries. 
|  4-3 

3-8 
12-0 
r  4-5 
\  berries. 
|  4-0 
3-0 
9-2 
9-0 
8-0 
10-0 
10.1 
8-6 
8-0 
14-0 
3-0 
r  2-9 
without  >- 
2-9 
2-0 
<  seeds  and  seed- 
pericarp.  J 
(.  vessels. 
f  3-0 
r  3-9 
-]  without 
J  2-0 
2-5 
-J  seeds  and  seed- 
(  pericarp. 
(.  vessels. 
4-0 
f  3-6 
X  before 
3-0 
flowering. 
12-0 
leaves  and  stems. 
6-0 
6-0 
4-8 
not  determined. 
7-2 
6-0 
6-0 
variable. 
Ripe 
berries. 
Name  and  Condition 
of  Plants. 
Belladonna  (Atropa 
Bellad.)  Highly  ma- 
nured.-  
Same  under  ordinary 
cultivation  
Foxglove  (Digitalis 
purpurea).  Wild.... 
Same,  transplanted 
to  a  rich  soil,  ma- 
nured slightly  
Stramonium  (Datura 
Stramon.)  Self-sown 
from  cultivat'd  plants. 
Same,  under  cultiva- 
tion  
Henbane  (Hyoscya-  ~\ 
mus  niger)  Cultiva-  >- 
ted  J 
Hemlock  ( Conium  mac- 
ulaturri)  Wild  
Dulcamara  (Solanum 
Dulcam.)  Wild  
The  effects  produced  by  situation  are  of  very  great  import- 
ance ;  a  proper  supply  of  air  and  moisture  should  form  the  first 
consideration  for  oil-yielding  crops,  and  the  soil  best  adapted 
should  contain  a  proper  proportion  of  silica,  alumina,  and  lime, 
which  seems  to  me  can  only  be  determined  experimentally  for 
each  crop. 
The  finest  specimens  of  chamomile  flowers  are  obtained  by 
carefully  laying  out  the  plants  in  rows,  not  nearer  to  each  other, 
on  any  side,  than  two  feet.    By  allowing  sufficient  space,  grow- 
