142 DR. F. E. FRITSCH ON THE 
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cells. Stone-cells are most markedly developed in J. mollis. Crystals generally oceur 
in some quantity in the cells of the primary cortex ; they are mainly clustered crystals, 
but solitary crystals are intermingled with them in small numbers.—Resin-canals are in 
all cases found in the primary cortex; they will be discussed more fully below. 
The secondary bast always contains at least one ring of large secretory canals and 
a second ring of smaller ones may appear in the inner portion in the course of secondary 
erowth. The canals of the main ring are each surrounded on the outer side by an are 
of thick-walled tissue, which probably represents the remains of the primary bast, each 
are corresponding to one of the original vascular bundles. The tissue in question 
consists of dead, more or less thickened cells, which are compressed by secondary growth, 
the walls being more or less undulated. In a longitudinal section it is difficult to make 
out the details accurately, but it is evident that the constituent cells are considerably 
elongated ; probably most of this tissue (for which some German authors have created 
the special name ** Hornbast ") consists of obliterated sieve-tubes of the primary phloem. 
The way in which these ares enclose the large resin-canals of the secondary bast is 
extremely characteristic and in every way recalls the appearance of a transverse section 
of the stem in the Anacardiacez.—For the rest, the secondary bast is characterised by 
the complete absence of bast-fibres. Clustered crystals generally occur abundantly in 
longitudinal rows of thin parenchymatous cells (chambered crystal-fibres), whilst solitary 
crystals are very rare; where they occur they are generally of rather large size. Within 
the mass of secondary bast one commonly meets with small groups of thick-walled tissue 
like those mentioned above as forming an arc round the larger resin-canals. 
The structure of the wood is very uniform in all the Julianiacez. The medullary 
rays are mostly only one, more rarely two cells in breadth, but never broader; in a 
transverse section the cells are oblong and more or less elongated in the radial direction ; 
in a radial longitudinal section they are rectangular, the long axis either being placed 
radially or vertically (horizontal or upright medullary ray cells). The walls are some- 
what thickened and provided with simple pits; the cells occasionally contain solitary 
erystals. Wood-parenchyma is almost entirely wanting in the secondary wood, but 
occurs in small quantity round about the primary vessels, The ground-mass of the 
wood is constituted by thick-walled wood-prosenchyma, the walls of which are provided 
with irregularly arranged slit-shaped simple pits; these elements are very commonly 
septate by means of thin partition-walls. The vessels are rather numerous (particularly 
so in Orthopterygium) and are irregularly disposed in a transverse section ; they are 
mostly isolated, but are sometimes found in groups of two or three together. They 
have lumina of medium size (maximum diameter = 65-70 u) and their shape is more or 
less circular. The perforations of the vessels are most commonly simple, although a few 
sealariform perforations are to be met with; in contact with the cells of the medullary 
rays the vessels bear large reticulately arranged simple pits on their walls, while other 
parts of the wall are provided with large simple or bordered pits. Spiral thickening 
does not occur in the secondary wood. 
The well-developed pith is made up of slightly thickened circular cells of varying size, 
the walls of which bear simple pits. In a longitudinal section the cells are rectangular 
