IN OIICHIDEjE AND ASCLEPIADEiE.

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ence, particularly in the parasitical tribes, of fibrous orspirally striated cells in the parenchyma, especially of theleaves, but also in the white covering of the radical fibres.

In the leaves, they are either short spirally striated cellswhose longer diameter is at right angles to the surface, asin Stelis and Pleurothallis, and whose fibres or striae areconnected by a broader membrane ; or, being greatlyelongated and running in the direction of the leaf, resemblecompound spiral vessels of enormous diameter, aud consist-ing entirely of the spiral fibres with no visible connectingmembrane : the real spiral vessels in the same speciesbeing, as they generally are in the family, very slender andsimple. In the white covering of the radical fibres theshorter striated cell is met with in many genera, especiallyI think in Oncidium and Epidendrum, in one species ofwhich they have been remarked and figured by Meyen . 1

My concluding observation on Orchidesc relates to thevery general existence and great abundance, in this family,of Raphides or acicular crystals in almost every part of thecellular tissue.

In each cell where they exist these crystals are ar-ranged in a single fasciculus, which is generally of a squareform.

The individual crystals,—which are parallel to eachother,—are cylindrical, with no apparent angles, and haveshort and equally pointed extremities.

The abundance of these fasciculi of crystals in the cellu-lar tissue of the auriculae of the column or supposed lateralstamina in Orphydeae, is very remarkable, giving these pro-cesses externally a granular appearance, which has been pisnoticed though its cause seems to have been overlooked.

In the recent work of Meyen , 2 also, some examples ofthese crystals in Orchideae are given.

Phytolomie, tab. 11, f. 1 and 2.

2 Phytotomie.