of Schizaea malaccana. 505 
mately tetrahedral shape, about twice as deep as it is broad 
(Fig. 10) ; in longitudinal section its side- walls appear nearly 
parallel to one another towards the free surface, and this 
character is correlated with the flatness of the apex. Some- 
times the apical cell and its immediate products occupy a pro- 
jection or papilla in the centre of the flat meristematic surface. 
This appears to be the case when growth is very feeble or 
at a standstill ; the products of segmentation are then much 
divided, and the resting apical cell has pushed out in front of the 
general meristematic surface. The apex is protected by 
numerous mucilage-producing hairs (/i., Fig. 10), which grow 
out from the cells of the meristematic surface quite close to 
the apical (the fourth or fifth cell from the apical has often 
already produced its hair), and bend inwards, usually quite 
covering the apex. Every one of the peripheral cells of the 
meristematic surface produces such a hair. Leaves are formed, 
together with adventitious roots, at a very early period, and 
one of the former often projects from the shoulder of the 
growing-point. The sequence of cell-divisions and the origin 
of the stem-tissues are not altogether easy to follow. This is 
due partly to the early origin of leaves and roots, the dividing 
tissues of whose rudiments sometimes force the stem-apex 
out of the central axis, and disturb the regular arrangement 
of the initials of the stem-tissues, and partly to the somewhat 
inconstant and irregular sequence of divisions in these last ; 
microtome-series are not easy to obtain, owing to the packing 
of the early-differentiated cortical cells with large starch- 
grains preventing thorough impregnation with paraffin and 
consequently causing the sections to break up under the knife. 
Owing to one or other of these causes we have comparatively 
few sections in which the whole course of histogenesis is 
perfectly clear, in spite of the considerable amount of material 
at our disposal ; but by carefully comparing a number of 
series, we have arrived at conclusions of whose correctness we 
have no doubt. We have figured a section in which the 
course of histogenesis is particularly clear (Fig. 10). 
Each segment cut off from the apical cell divides first by 
