NON-PROTOPLASMIC CELL CONTENTS 89 
tubers of Solanum tuberosum and varieties of Dahlia, and is known 
to play an important part in metabolism. Stevens claims that 
proteids are reduced for the most part to asparagine during 
seed germination.! If thick sections are cut from a plant part 
containing this substance and mounted in alcohol, rhombohedral 
crystals of asparagin in the form of plates will be deposited upon 
the evaporation of the alcohol. _ If to these a few drops of a satu- 
rated solution of asparagine are added the crystals already formed 
will increase in size. To get satisfactory results the saturated 
solution must be of the same temperature as the mount. 
11. Catcrum OxALATE.—This substance occurs in many 
plants always in the form of crystals. It is formed by the reac- 
tion of salts of calcium, which have found their way into the cell 
sap from the soil, with oxalic acid which is manufactured by the 
plant as a by-product of protein synthesis and other metabolic 
processes. Calcium oxalate crystals dissolve readily in mineral 
acids without effervescence. They are insoluble in acetic acid or 
water. These crystals are classified according to form and belong 
either to the monoclinic or tetragonal system. (See Fig. 51.) 
Crystals belonging to the monoclinic system possess 3 axes of 
unequal length, two of which are obliquely inclined to each other, 
the other axis forming right angles with these two. ‘They appear 
to be more frequently found in plants than those of the tetragonal 
system. | 
Crystals belonging to the tetragonal system have 3 axes at 
right angles to each other; two of the axes are equal in length, the 
third being of a different length. 
CRYSTALS BELONGING TO THE Mownoc.inic SysTEM AND 
ExampLes oF Drucs ConTaAInING THEM: 
1. Solitary—Hyoscyamus, Acer Spicatum, Viburnum 
Prunifolium. ; 
2. Rosette Aggregates (Druses)—Althza, Gossypii Radicis 
Cortex, Stramonium, Granatum, Rheum, Foeniculum, Vibur- 
num, Eucalyptus. 
3. Columnar (Styloids)—Quillaja, Tris. 
4. Raphides—Convallaria, Sarsaparilla, Veratrum Viride, 
Scilla, Phytolacca, Ipecacuanha, Hydrangea. 
1 Stevens’ Plant Anatomy, 3d Edit., p. 189. 
