ABSTRACT
The cutting of air-dried tissues inevitably gives the casting agent access to every intercellular and intracellular space and canal, as well as to certain files of parenchyma cells and, under particular conditions, to the phloem. The canals and spaces are intercellular spaces of accumulation, storage, and circulation of liquid substances produced by the bordering cells or of gas of composition similar to that of air. The casting of parenchyma cells is generally confined to the immediate vicinity of cross-sections. The penetration of the elastomer into whole cells depends on undetermined factors that affect the permeability of the primary wall or cause it to tear. A preliminary freeze-drying often favours the casting of aggregates of whole cells in the medullary parenchyma and also, via the adjacent vessels, in the radial parenchyma. The secretory cells are differentiated in the parenchyma of the cortex, of the pith, and of the wood.
