AREOLATED DOTS. 153 
obtuse cone, in so far as the walls of the canal are not superposed 
perpendicularly to the wall of the cell. If in this manner the 
canal becomes narrower toward the interior, it finally corre- 
sponds in form to a somewhat dilated funnel. The upper edge 
corresponds to the place in the wall which has remained un- 
thickened, and within this circle or border the aperture of the 
funnel toward the cell-cavity appears as a pit. 
Similar areolated pits are wont to appear simultaneously at 
such places where two cells come in contact by the surface of 
their walls; the intervening wall, which, moreover, does not 
always lie in the median line of the pit, but is often, as in 
Fie, 70.—Thickened cells with pore-canals. A, Bast-fibre of a Cinchona Bark, B, 
Stone-cells from a nut-shell. (8 from Dippel.) 
Fig. 64, d, e, f, pressed against one of the apertures (wood-cells 
of the Conifers), disappears by age, so that the space occupied 
by the pit establishes a direct connection between the two cells 
(Fig. 72, A, C). These hollow spaces, which sometimes resem- 
ble two funnels, one inyerted over the other, and which are | 
sometimes arched in a more lens-shaped manner (Fig. 72), are 
easily recognizable where they occur more isolated. If, however, 
they are formed in larger number closely beside each other, and if, 
through increasing thickening, they become gradually contracted 
in a cleft-like form, more complicated relations are produced, 
