A™'ctJo°bTr,  i9iorm'}  Rhizome  and  Roots  of  Phlox  Carolina.  475 
pointed  or  oblique  ends,  and  from  100  to  300  microns  in  length. 
Somewhat  similar  stone  cells  are  found  in  the  stem  of  Phlox  pilosa 
L.  If  the  material  containing  these  cells  should  be  relatively 
abundant  in  a  mixture,  their  presence  would  give  another  character 
for  distinguishing  the  rhizome  of  Phlox  from  that  of  Spigelia. 
The  stone  cells  in  Euellia  are  different  in  shape,  and  in  addition 
are  associated  with  cells  containing  calcium  carbonate.  The  presence 
of  these  special,  thick-walled  lignified  cells  in  the  rhizome  of  Phlox 
may,  however,  be  of  infrequent  occurrence,  like  the  bast  fibres 
in  belladonna,  which  I  have  only  occasionally  seen,  but  which  have 
been  described  by  Schrenk,  and  therefore  may  not  be  of  assistance 
in  the  identification  of  the  drug.  It  might  be  mentioned  in  this 
connection,  however,  that  groups  of  bast  fibres  have  been  found  in 
Phlox  aristata  Michx.,  and  a  ring  of  bast  fibres  in  the  stem  of 
Phlox  longifolia  Nutt,  P.  Douglassi  Hook.,  and  P.  acuminata 
Pursh. 
Histological  Characters  of  Root. — A  transverse  section  of 
the  root  shows  (1)  ordinary  epidermal  cells  with  root-hairs;  (2) 
a  hypodermis  made  up  of  radially  elongated,  more  or  less  pentag- 
onal cells;  (3)  a  cortex,  consisting  of  12  to  20  rows  of  ellip- 
soidal rather  thin-walled  parenchymatous  cells,  which  are  rich  in 
protoplasm  and  may  contain  small  starch  grains;  (4)  a  peripheral 
layer  of  the  central  cylinder;  (5)  endodermis ;  (6)  internal  hyer 
of  cortex,  and  (7)  within  this  there  is  in  the  very  young  roots  a 
triarch  to  pentarch  radial  fibrovascular  bundle,  which  later  becomes 
collateral  and  closely  resembles  in  structure  that  of  the  rhizome. 
While  the  stem  is  free  from  hairs  the  leaves  have  rather  striking 
glandular  hairs  (Fig.  G),  which  are  found  on  the  principal  veins 
near  the  base  of  the  leaf.  The  histological  characters  of  the  leaf 
have  been  very  well  given  by  Holm,  and  it  therefore  does  not 
seem  necessary  to  consider  them  here. 
I  may  say  in  conclusion  that  I  am  engaged  in  the  study  of 
the  structure  of  the  underground  parts  of  other  species  of  Phlox, 
as  possibly  the  rhizomes  and  roots  of  other  species  may  occur  as 
admixtures  in  drugs,  and  besides  the  genus  is  of  great  interest 
botanically. 
LITERATURE  CITED. 
1  Kraemer :   "A  Course  in  Botany  and  Pharmacognosy,"  1902,  p.  157. 
2  Pharmaceutical  Reviezv,  25,.  pp.  2,  33,  65,  97  (1907). 
3  Am.  Jour.  Pharm.,  78,  p.  553;  79,  p.  51  (1907). 
4  Pharm.  Jour,  and  Trans.,  21,  p.  839  (1891)  ;  Am.  Jour.  Pharm.,  63,  p.  226 
(1891). 
