272  Content  of  Ash  of  Certain  Drugs.   {Am-AJp°r"1r-  f^™' 
Results  and  Discussion. 
The  results  obtained  are  tabulated  below  and  are  calculated  on 
the  dry  basis  at  no°  : 
Table  I. 
Drug  Examined.  Per  Cent,  of  Manganese  Present. 
Rhamnus  Frangula  (or  alder  buckthorn  bark)           0.0242  to  0.0674  +  0.0003 
Cinnamomum  Cassia  Cortex  (or  cassia  bark)  . . 
. .  0.0624 
+  0.0003 
Rhamnus  Purshiana  (cascara  sagrada)   
.  .  0.0137  to  0.0223  +  0.0003 
Podophyllin  (root)   
+  0.0002 
..  0.0043 
+  0.0002 
+  0.0002 
Rhamnus  Californica  (mature  bark)   
. .  0.0033 
+  0.0002 
+  0.0001 
+  0.0001 
Euonymus  Atropurpureus  (wahoo  bark)   
0.0021 
+  0.0001 
+  0.0001 
Aloes  (barbadoes)   
.  .  0.0006 
+  0.00005 
From  data  available  it  would  appear  that  both  Rhamnus 
Frangula  and  cassia  bark  show  a  higher  content  of  manganese  than 
any  other  similar  plant  tissue  previously  examined.  It  was  found 
that  all  samples  of  these  barks  did  not  show  the  same  manganese 
content,  and  observed  limits  of  the  amounts  present  are  given  above. 
The  lower  numbers  represent  mature  or  thick  bark,  while  the  higher 
numbers  were  obtained  from  thinner  bark.  It  is  quite  possible  that 
an  examination  of  specially  selected  bark  would  widen  this  range, 
but  the  work  reported  was  carried  out  on  various  samples  and  it  is 
thought  that  it  covers  the  range  fairly  well.  Factors  involving  the 
change  of  manganese  content  with  the  season  have  not,  however, 
been  studied.  In  an  attempt  to  locate  the  cells  or  region  of  the  bark 
giving  the  highest  content  of  manganese,  both  inside  and  outside 
scrapings  were  examined.  It  was  found  for  Rhamnus  Purshiana 
that  the  concentration  of  manganese  in  the  inner  third  of  the  bark 
was  about  double  that  present  in  the  outer  third.  This  may  indeed 
be  generally  true  and  would  go  to  show  that  although  manganese  is 
present  in  the  outer  layers  of  the  bark  it  really  functions  more  par- 
ticularly in  the  inner  layers  where  plant  metabolism  is  more  actively 
going  on.  The  accidental  presence  of  definite  amounts  of  man- 
ganese in  these  barks  cannot  be  accepted  as  an  explanation,  while 
the  conception  that  a  definite  concentration  of  manganese  is  a  factor 
in  the  normal  metabolism  of  any  particular  species  seems  more 
probable.    It  is  natural  to  expect  that  a  plant  using  a  higher  con- 
