CALCIUM OXALATE. 129 
variable, in many cases very slight, as for instance in Rhizoma 
Arnice. From dried Radix Inule, on the other hand, Dragen- 
dorff obtained 44 per cent of inulin; from the root of Taraza- 
cum, gathered at Dorpat, Russia, in October, and dried at 
100° C., 24.3 per cent, while the same root in March afforded 
only 1.7 per cent of inulin. 
The great periodical fluctuations, and the want of a reagent, 
may explain why it has not yet been possible to detect inulin 
in many roots of perennial Composite. 
Although inulin never occurs in crystals in the living and 
dried plant, there are other crystalline substances which occur 
not infrequently in the tissue of the cell. Calcium oxalate 
especially is widely distributed. 
In yery many plants calcium is deposited in the cells in the 
form of distinctly crystallized oxalate. ‘his salt mostly corre- 
sponds to the formula CaC,0,+ H,O, and belongs to the mono- 
clinic (clino-rhombic) system of crystals. Occasionally, how- 
ever, forms of the quadratic or tetragonal system are also to be 
seen ; this variety of oxalate contains 3H,0. 
When calcium oxalate is prepared artificially, and the salt 
Separates rapidly, the first-mentioned compound is obtained 
either as an indistinct crystalline precipitate, or in well recog- 
nizable monoclinic forms; the quadratic oxalate, on the con- 
trary, crystallizes during the slow evaporation of a hydrochloric 
acid solution, or also upon the admixture of very little calcium 
chloride with an extremely dilute solution of oxalic acid.‘ Fre- 
quently, under slightly changed conditions, a mixture of both 
compounds is produced. 
The two forms of calcium oxalate are of exceedingly frequent 
occurrence in the vegetable kingdom. The needle-shaped crys- 
tals, rhaphides* (Fig. 55), appear to belong to the monoclinic 
' With regard to the more precise conditions, compare Souchay and 
Lenssen, Annalen der Chemie u. Pharm., 100 (1856), 311-325. 
* From fais, the needle. A. de Candolle, in 1826, introduced the 
term raphides, in order to avoid the use of the word crystals, as he sup- 
posed (erroneously) those deposits of oxalate of calcium not to consist 
of crystals, 
