CELL CONTENTS 205 



instance, are blue or violet. Most of the smaller rosette crystals, 

 however, appear grayish white with a darker-colored centre. 



Rosette crystals occur in parenchjona cells (Plate 8i, Fig. 4) 

 and in medullary rays (Plate 81, Fig. 3). 



SOLITARY CRYSTALS 



Solitary crystals are the most variable of all the forms of 

 calcium oxalate. They usually occur in crystal cells associated 

 with bast fibres and stone cells, less frequently in stone cells 

 (Plate 33, Fig. 2). There are many different and characteristic 

 forms of prisms. The more common are: 



1. Rectangular: 



A. Parallelopipeds. 



B. Cubes. 



2. Polyhedrons: 



A. Irregular polyhedrons. 



I. Flat bases. 



(a) Non-notched. 



(b) Notched. 

 II. Tapering bases. 



B. Octohedrons. 



The crystals occurring in Batavia cinnamon and henbane 

 leaves are parallelopipeds (Plate 82, Figs, i and 2). 



The crystals occurring in cactus grandiflorus, hemlock bark, 

 krameria root, and soap bark are irregular polyhedrons (Plate 

 83). They are longer than broad, and the ends are tapering. 

 The crystal of cactus grandiflorus has the narrowest diameter 

 of these four, while the crystals of soap bark have the widest 

 diameter. In coca leaf, xanthoxylum bark, elm bark, Spanish 

 licorice, and in white oak (Plate 84), and in cocilUna bark (Plate 

 82, Fig. 4) the crystals are all irregular polyhedrons with flat 

 bases. They are mostly longer than broad and they are all 

 widest in the centre; in each a few crystals are notched, but 

 most of the crystals are not notched. 



The crystals in quassia wood, uva-ursi leaf, and most of those 

 of quebracho and wild cherry bark (Plate 86, Figs, i, 2, 3, and 4) 

 are irregular polyhedrons with flat ends. They are longer than 

 broad, widest at the centre, and non-notched. 



Cubes occur in senna, cascara sagrada, frangula, white pine, 



