Aroc^ober,PlSoa^m•}         Calcium  Oxalate  Crystals.  475 
Glycyrrhiza,  15-20  microns. 
Hamamelis,  7-20  microns. 
Haematoxylon,  10-15  microns. 
Prunus  Virginiana,  20-30  microns. 
Quercus  alba,  10-20  microns. 
Quillaja,  about  35  microns. 
Rhamnus  purshiana,  5-20  microns. 
Santalum  rubrum,  7-15  microns. 
Ulmus,  10-25  microns.. 
Uva  Ursi,  7-10  microns. 
4.  Raphides  was  the  name  given  by  A.  de  Candolle  (1826)  to  the 
groups  of  needle-shaped  crystals  found  in  various  plants.  These 
have  been  mistaken  by  several  observers  for  calcium  phosphate.1 
Usually  the  cells  containing  raphides  are  long,  thin-walled  and  con- 
tain sooner  or  later  a  mucilage,2  which  arises  from  the  cell  sap  and 
behaves  with  reagents  much  like  cherry-gum.  The  cells  are  either 
isolated  or  occur  in  groups  placed  end  to  end,  as  in  Veratrum  viride, 
forming  Hanstein's  "  Raphidenfuhrenden  Schlauchgefasse."  Ra- 
phides are  found  in  the  following  drugs,  and  of  the  length  given  with 
each : 
3  Belladonnse  folia,  occasionally. 
Cinnamomum,  about  5  microns. 
Convallaria,  about  45  microns. 
Cypripedium,  about  40  microns. 
Ipecacuanha,  20-40  microns. 
3  Phytolacca  radix,  about  30  microns. 
Sarsaparilla,  6-8  microns. 
Scilla,  o-i  to  i*o  mm. 
Vanilla,  about  400  microns. 
Veratrum  viride,  about  45  microns. 
5.  Cryptocrystalline  crystals  of  calcium  oxalate  are  exceedingly 
small  (about  -2  to  10  microns  in  diameter)  deltoid  or  arrow-shaped, 
and  are  so  numerous  as  to  entirely  fill  the  parenchyma  cells  in 
which  they  occur,  giving  the  cells  a  grayish-black  appearance  and 
readily  distinguishing  them  from  other  plant  cells.  Vesque  sup- 
posed that  they  were  tetrahedrons  and  termed  them  "  Sable  Tetrae- 
1  Calcium  phosphate  is  apparently  seldom  found  in  plants  except  either  in 
solution  or  in  combination  with  protein  substance. 
2  Kraemer  im  Am.  Jour.  Pharm.,  1898,  225. 
3  Cryptocrystalline  crystals  also  occur. 
