42 
ORGANOGRAPHY. 
BOOK I. 
any. They are insoluble in alcohol, water, and caustic pot- 
ash, but are dissolved by nitric acid. 
Raphides are found solitary in the cells of Papyrus anti- 
quorum, Epidendrum elongatum, &c., scattered in consider- 
able numbers in the cells of Musa paradisiaca and collected 
firmly into bundles which are a little shorter than the cells in 
which they lie. They are in most instances formed in the cells 
of Merenchyma and Parenchyma without order ; but Meyen 
has observed that in the bark of Viburnum Lantana they are 
principally stationed in the interior of thin-sided cells, clus- 
tered in cavities of thicker sided tissue. 
Link compares the raphides in plants to calculi in animals. 
Raspail asserts that raphides are never found either in 
Cactus or elsewhere in the inside of the bladders of cellular 
tissue, but are exclusively placed in the intercellular passages. 
The slender kind [Jig. 13.) he states to be crystals of phos- 
phate of lime, from to of a millimetre in length, and 
to be in reality six-sided prisms, terminated at each end by a 
pyramid with the same base. The crystals found in the 
Cactus and Rhubarb (^^5.1 Land 12.), he says are composed of 
oxalate of lime ; and he represents them to be right-angled 
prisms, terminating in a four-sided pyramid. [Nouv. Syst. 
de Ch. Org. p. 522.) According to Marquartthe raphides of 
Aloe arborescens consist of phosphoric acid combined with 
lime and magnesia. Mohl says that raphides are never six- 
sided prisms, as Raspail asserts ; but that they are right- 
angled four-sided prisms, which gradually vanish into points ; 
and he declares that Meyen is right in asserting that the 
raphides are constantly formed inside the bladders, and never 
in the interstitial passages of cellular tissue [Anat. Palm. 
p. 28.) ; about which there is no sort of doubt. In Liparis 
pendula, in which the tissue is very thin, the raphides may 
be seen in situ without disturbing the surrounding parts, 
and they then form dense bundles of acicular crystals lying 
in the centre of cells. 
The same circumstance is particularly visible in the oval 
cells found in the leaves of Caladium esculentum, Dieffen- 
bachia Seguina, and some other Araceae. Here the acicular 
raphides are not only collected in bundles inside the cells, but 
