The crystals of prismatic habit represented in figs.
Crystals are prismatic, acicular or scaly in habit; they have a perfect cleavage parallel to the brachypinacoid (M in the figure).
Owing to the sacrifice of form to prismatic brilliance, cut-glass gradually lost its artistic value.
In some Pteridophyte stems the apical eel is wedge-shaped, in others prismatic; in the latter case segment~
In the Fucaceae, on the other hand, there is a single prismatic apical cell situated at the bottom of a groove at the growing apex of the thallus, which cuts off cells from its sides to add to the peripheral, and from its base to add to the central permanent cells.