140 DR. F. E, FRITSCH ON THE 
of which are commonly in a state of disorganisation. In this stage, therefore, the 
further development of the canals is apparently lysigenous. According to Sieck * such 
schizolysigenous secretory canals occur also in the Anacardiaces. In the J ulianiacere, 
however, lysigeny only appears to set in in older stages, since the smaller canals in the 
lamina and in the petiolar cortex are purely schizogenous. Besides the regular canals 
of the phloem, which lie opposite to the xylem-groups of the buudles, other (generally 
smaller) canals are found lying between the ordinary ones; these stand in no evident 
relation to the bundles and are possibly of later development. ‘The phloem of the 
petiolar bundles of Orthopterygiwm contains numerous clustered crystals. 
Resin-canals are also present in the pith of the petiole in Juliania adstringens. 
The structure of the rachis (i.e. of the part of the central axis of the leaf bearing the 
leaflets) is very much like that of the petiole. The bundles form a complete somewhat 
flattened ring, which otherwise shows no indications of dorsiventrality. The secretory 
canals in the phloem are strikingly large. Just below the point at which two opposite 
leaflets arise the rachis broadens out and the vascular ring becomes still more flattened, 
From each edge of the flattened ring a number of bundles bend out into the leaflet, the 
gaps in the vascular ring of the rachis thus produced closing up again at a slightly 
higher level. 
(c) The Connection between the Vascular System of Stem and Leaf. 
The relation between the vascular system of the stem and that of the leaf could only 
be determined in Juliania adstringens, of which a limited amount of spirit-material was 
available. The apex of the branches on which the clusters of leaves are borne is slightly 
flattened, which also finds expression in the outline of the vascular ring; the latter 
consists of a number of well-marked bundles separated by rather broad medullary rays. 
The stem at this point contains a superabundance of resin-canals in all parts of the 
ground-tissue, their number being especially striking in the pith. A little way below 
the insertion of a leaf the bundles situated on that side of the stem from which the leaf 
arises are found to approximate to one another, so that the intervening rays almost 
disappear. At a slightly higher level the almost compact plate of vascular tissue thus 
produced shows the first signs of a bulging out towards the outside, and this becomes 
more extensive as sections at progressively higher levels are examined ; this protruded 
portion of the vascular system of the stem is ultimately cut off to supply the petiole. 
The rather considerable number of xylem-vessels found in these bundles in the stem 
becomes gradually distributed in a much thinner layer in the protruded portion (petiolar 
system). "The latter at first merely looks like a little side-loop of the main vascular ring 
of the stem ; at higher levels, however, it becomes very much expanded (and tangentially 
flattened) distally, while that part of it which lies next to the vascular system of the stem 
narrows down very considerably before joining up with the latter, so that the point of 
connection between the petiolar loop and the bundle-ring of the stem is rather a narrow 
one. Sections taken at a still higher level show the complete detachment of the petiolar 
* Pringsheim’s Jahrb. Bd. xxviii. 1895, pp. 227 et seq. 
