134 ; PLANT ANATOMY. 
through several cells, after their transverse walls are destroyed” 
These crystals often attain nearly 1 mm, in length, so that they | 
become visible even to the unaided eye. The latter character 
applies also to the imperfectly developed, rhombohedron-like 
erystals in the wood-parenchyma of Lignum Sandali rubrum, 
the axes which are scarcely less than $ mm. 
According to Emmerling* it would appear probable that 
erystals of calcium oxalate are also formed in the plant through 
the action of free oxalic acid upon calcium nitrate. 
In the cases here referred to, calcium oxalate always occurs as. 
one of the contents of the cell; it has been shown, however, by 
Count Solms-Laubach * that these crystals may also be deposited 
in the cell-wall itself, especially in the outer wall of epidermis 
cells. 
In regard to the amount of oxalate, the microscopical estimate 
may lead toinaccurate statements. Bulbus Scille is apparently 
rich therein, and nevertheless,a direct estimation of the oxalic 
acid afforded but 3 per cent of oxalate; in a good rhubarb * one 
of us found 7.3 per cent. The greatest abundance of oxalate in 
the domain of pharmacognosy is presented perhaps by guaiac 
bark, nearly 20.7 per cent. Some lichens are likewise charac- 
terized by a large amount of oxalate; thus Lecanora esculenta 
Eversmann, contains 22.8 per cent. 
The oxalate crystals are deposits which remain withdrawn 
from the sphere of vital action (secretions); in the cells which 
contain them, as a rule, no further developments take place. 
Other crystalline compounds of inorganic bases are of exceed- 
ingly rare occurrence in plant tissues. Calcium phosphate, 
? “ Berichte der Deutschen Chemisch. Gesellsch.,” 1872, p. 782. 
* Botanische Zeitung, 29 (1871), 458. Plate VI.— Also in Sachs, ‘‘ Lehr- 
buch der Botanik,” 1874, 68. 
_ 8 One of the numerous important observations of the eminent apothe- 
cary Scheele, who also discovered oxalic acid, relates to the crystals of 
rhubarb, which, in 1782, he recognized as calcium oxalate. Anton van 
Leeuwenhoek (1716) had, indeed, previously seen the oxalate of the 
sarsaparilia root and of orris ont —Flickiger, ‘‘ Pharmakognosie,” 
2d edition, 226, 315, 373. 
