ANATOMY OF THE JULIANIACE X. 137 
elongated gland of J. mollis that is really characteristic ; very often there is a pre- 
ponderance of short glands, which are very like those of J. amplifolia. In J. glauca 
and J. adstringens (fig. 1, E) the glands rather resemble those of J. amplifolia in shape, 
but the actual glandular portion is mostly well demarcated and vertical division-walls 
are rather common ; in some cases they show a definite arrangement, so that the 
glanduiar portion consists of four-celled tiers. In Orihopterygium Huaucui the 
glandular hairs are rather distinctive ; they are, on the whole, very short and somewhat 
globular in shape, with a much reduced unicellular stalk. The globular multicellular 
head exhibits both horizontal and vertical division-walls, which often divide it up into a 
number of alternating tiers of four cells each (fig. 1, D, F). 
The mesophyll, as a rule, shows a well-marked differentiation into palisade and 
spongy tissue, although in Juliania mollis and J. adstringens the lower layer of the 
spongy tissue tends to develop into palisade. The ordinary palisade-tissue in all cases 
consists of a single layer of cells, which are much elongated and have a very small 
diameter. The lateral walls are finely undulated in Orthopterygium. Seen from the 
surface the palisade-cells appear small and round; in O. Huaucui there are palisade- 
cells of two more or less distinct sizes.— The spongy tissue is, as a rule, rather dense and 
is not infrequently present only in small quantity, the palisade-tissue occupying a much 
greater portion of the width of the leaf than the spongy tissue. The lowest layer 
of the latter generally shows a somewhat palisade-like elongation, which, as above 
mentioned, is well pronounced in Juliania mollis and J. adstringens. In some specimens 
of the latter species (Rose and Hay, 5341) no proper spongy tissue is developed ; on the 
lower side of the leaf there are two layers of palisade consisting of short rounded- 
rectangular cells, which are much wider and shorter than the ordinary palisade-cells 
below the upper epidermis. The upper epidermal cells in these same specimens, as will 
be remembered (cf. p. 134), have a slightly columnar shape. In this way the entire 
transverse section of the leaf acquires a very characteristic stratified appearance, which 
is slightly represented in all the members of the Order. 
Scattered about in the mesophyll are large clustered crystals of varied shape, which 
generally occupy somewhat enlarged idioblasts. The latter are mostly found lying 
immediately beneath the upper and lower epidermis, and are in most cases confined to 
the neighbourhood of the numerous small veins of the leaf ; in Orthopterygium they are 
also met with round about the bases of some of the hairs. A considerable number of 
clustered crystals are generally present also in the collenchyma forming the ribs of the 
larger veins; this is especially the case on the lower side of the leaf, on which the course 
of the veins is often marked by the numerous crystals. In Juliania amplifolia and 
J. adstringens the clustered crystals are particularly large and occupy correspondingly 
large idioblasts. No other form of excretion of oxalate of lime is met with in the leaf. 
Turning, lastly, to a consideration of the vascular system of the leaf, we meet with one 
of the chief points of resemblance between this Order and the Anacardiaceze. I refer to 
the occurrence in the phloem of large canals containing resin. This character is common 
to all the five species of the Julianiaceæ, the secretory canals even being present in 
the finer ramifications of the vascular system, which traverse the leaf in all directions. 
SECOND SERIES.—BOTANY, VOL. VII. d 
