714 Mr. Brown on the Organs and Mode of 
The second point of structure in Orchidez to which I shall 
at present more briefly advert, is the frequent existence, parti- 
cularly in the parasitical tribes, of fibrous or spirally striated 
cells in the parenchyma, especially of the leaves, but also in the 
white covering of the radical fibres. 
In the leaves, they are either short spirally striated cells 
whose longer diameter is at right angles to the surface, as in 
Stelis and Pleurothallis, and whose fibres or stria are connected 
by a broader membrane; or, being greatly elongated and run- 
ning in the direction of the leaf, resemble compound spiral 
vessels of enormous diameter, and consisting entirely of the 
spiral fibres with no visible connecting membrane: the real 
spiral vessels in the same species being, as they generally are 
in the family, very slender and simple. In the white covering 
of the radical fibres the shorter striated cell is met with in many 
genera, especially I think in Oncidium and Epidendrum, in 
one species of which they have been remarked and figured by 
Meyen*. 
My concluding observation on Orchidee relates to the very 
general existence and great abundance, in this family, of Ra- 
phides or acicular crystals in almost every part of the cellular 
tissue. 
In each cell where they exist these crystals are arranged in a 
single fasciculus, which is generally of a square form. 
The individual crystals,—which are parallel to each other, — 
are cylindrical, with no apparent angles, and have short and 
equally pointed extremities. 
The abundance of these fasciculi of crystals in the cellular 
tissue of the auriculæ of the column or supposed lateral stamina 
in Ophrydeæ, is very remarkable, giving these processes exter- 
* Phytotomie, tab. 11. f. 1 & 2. 
nally 
