332 BOTANICAL GAZETTE [NOVEMBER 
cannot be split apart, and even as late as May, when the stony layer 
has become very hard, the fleshy layer cannot be peeled off; it is only 
after it has become somewhat dry that it can be peeled off from the 
stony layer. However, the two layers easily separate as early as 
December if an ovule is cut in two and then allowed to decay for a 
few days in a damp atmosphere. The walls of the epidermal cells 
are considerably thickened and the outer surface is strongly cutinized. 
Most of the cells of the two layers just beneath the epidermis contain 
tannin, which occurs in only less abundance down to the level of the 
outer bundles. The cells containing tannin lie mostly in rows extend- 
ing in the same general direction as the bundles. The large mucilage 
canals lie between the bundles and also have a general vertical course, 
but they branch and sometimes anastomose, so that some transverse 
sections of the canals are found even in longitudinal sections of the 
ovules. Beyond the zone of the bundles is a region of parenchyma 
cells (fig. 11, p). 
The stony layer—This layer, except at the deep pit which is occu- 
pied by the basal papilla, is thickest at the base and thinnest at the 
extreme apex. From the thin spot at the apex down to the lower part 
of the free portion of the nucellus it is thicker than throughout the” 
middle two-thirds of the ovule. While the stony layer of the ripe 
seed is extremely hard, it is tougher and more elastic than the stony 
-coat of most nuts, doubtless due to its complicated structure. The 
outer cells of the layer are small and isodiametric (jig. 11, i). In 
November they are not very sharply marked off from the inner cells 
of the outer fleshy layer; in fact, it is only after the walls of the stone 
cells have begun to thicken that the boundaries of the layers can be 
determined with accuracy. Beyond the small isodiametric cells nae 
irregular zone of cells elongated in a more or less longitudinal direction 
(jig. 11, e); then follows a zone of similar cells elongated transversely 
(fig. 11, et); and finally another zone of cells considerably elongat 
longitudinally (fig. rz, 7). As growth continues, the small — 
isodiametric cells simply increase in size and their walls became thick- 
ened. In the cells of the other three regions there is not only an 
increase in size and a thickening of the walls, but various displace- 
ments occur, so that the structure in March is much more complicated 
than in the preceding November. The elongating cells become 
