Ao'iober,Pi90Lm-}         -Calcium  Oxalate  Crystals.  473 
(5)  Cryptocrystalline  crystals. 
(6)  Membrane  crystals. 
1.  Rosette  Aggregates  consist  of  numerous  small  prisms  and  pyra- 
mids or  hemihedral  crystals  more  or  less  regularly  arranged  on  a 
central  crystal  and  having  the  appearance  of  a  rosette  or  star. 
The  development  of  this  form  may  be  readily  followed  in  the  stem 
of  Datura  stramonium  L.  This  form  is  more  largely  represented 
in  our  drugs  than  any  other  form  and  the  following  is  a  list  of  the 
pharmacopceial  drugs  in  which  the  crystals  of  this  class  are  con- 
tained, together  with  the  size  of  the  crystals  : 
Althaea,  25  microns. 
Anisum,  2-3  microns. 
Belladonnae  folia,  occasionally. 
Buchu,  15-25  microns. 
Calendula,  4  microns. 
Cannabis  indica,  about  20  microns. 
Carum,  0.5-1.0  microns. 
Caryophyllus,  10-15  microns. 
Chimaphila,  40-60  microns. 
Conium,  1-2  microns. 
Coriandrum,  3-7  microns. 
Cusso,  about  20  microns. 
Briodictyon,  20-25  microns. 
Euonymus,  15-20  microns. 
Foeniculum,  1-2  microns. 
1  Frangula,  5-20  microns. 
Geranium,  45-70  microns. 
Gossypii  radicis  cortex,  about  20  microns 
1  Granatum,  about  15  microns. 
Humulus,  10-15  microns. 
Jalapa,  30-35  microns. 
Pilocarpus,  20-30  microns. 
Pimenta,  10  micron  ;  occasionally  25  microns. 
Prunus  Virginiana,  20-30  microns. 
Quercus  alba,  10-20  microns. 
1  Rhamnus  purshiana,  5-20  microns. 
Rheum,  50-100  microns. 
Rubus,  25-30  microns. 
Stillingia,  about  35  microns. 
Viburnum  opulus,  occasionally. 
Viburnum  prunifolium,  15-35  microns. 
2.  Monoclinic  Prisms  and  Pyramids. — Next  to  the  rosette  aggre- 
gates the  prisms  and  pyramids  occur  in  the  greatest  number  of 
1  In  these  drugs  prisms  and  pyramids  in  group  No.  2  also  occur. 
