132 PLANT ANATOMY. 
the individual crystals just project, but the true erystallographi- 
cal shape of the latter has not yet been determined with certi- 
tude. The fact that in Cortex Cascarille, in Cortex Frangule, 
in the outer surface of Fungus Laricis, in the above-mentioned 
Styrax bark, and in other cases they are accompanied by dis- 
tinctly recognizable monoclinic crystals of oxalate, argues possi- 
Fia. 60.—Fundamental forms of calcium oxalate‘crystallizing in the quadratic system 
with three molecules of water of crystallization. 
bly for the assumption that these aggregates or rosettes also. 
belong to this system, although in the above-mentioned leaf- 
Fic. 61.—Transverse section from an ordinary (Aleppo) oak-gall; d, sclerenchyma- 
tous layer in the centre ; ¢, tissue outside of and in proximity to this layer, filled with 
quadratic crystals of oxalate ; e, tissue in the interior of the chamber formed by the 
sclerenchyma, which contains starch and resin. * 
stalks all transitional forms may also be observed, from the 
quadratic octahedron to imperfectly developed rosette-shaped 
aggregates of crystals. Hence it is probable that the oxalate 
crystallizing in rosettes sometimes belongs to the quadratic and 
sometimes to the monoclinic system. 
