138 DR. F. E. FRITSCH ON THE 
Two species of Anacardiacese (viz. Rhus simulata and Spondias mangifera), which I 
examined for comparison, both possess such resin-canals in the leaf in exactly the same 
position. The canals are restricted to the phloem of the vascular bundles and are not 
found elsewhere in the tissue of the leaf. The cavity of the resin-canals is lined bya 
single well-marked layer of thin parenchymatous cells, appearing more or less rounded 
in a transverse, and slightly elongated in a longitudinal section. The mode of 
development of the canals is apparently schizogenous (cf. fig. 2, A & B, of the petiole). 
‘The contents appear as a yellowish or reddish-brown mass insoluble both in Eau de 
Javelle and in alcohol. One such canalis present in the bast of each vascular bundle, 
and, where the veins comprise a number of bundles, there is a corresponding number of 
resin-canals. 
A, B.—Juliania adstringens (Rose & Hough, n. 5341), resin-eanals from the petiole in transverse section, showing 
stages in their development.—A, early stage ; B, more advanced stage. (x 680.) 
C.— Juliania glauca, resin-canal from the pith of the stem, in transverse section. (x 215.) 
The chief veins of the leaf, except in Orthopterygium, usually have well-developed 
collenchymatous ribs projecting on the under side. There are only a few xylem-vessels 
present, and the greater part of the phloem is occupied by the resin-canals, so that the 
amount of vascular tissue in each bundle is small, This is compensated for by the rich 
ramification of the vascular system, giving rise to the numerous small bundles seen in 
a transverse section and consisting largely of spiral tracheids. In Orthopterygiwm many 
of these elements have enlarged terminations. The phloem commonly contains small 
clustered crystals. There is never any sclerenchyma accompanying the bundles, such 
mechanical elements being completely absent from all parts of the leaf. 
(b) The Petiole and Rachis. 
The structure of petiole and rachis could only be examined in Juliania adstringens 
(Rose & Hay, 5341) and Orthopterygium Huaucui. There are no very marked differences 
between the two cases, and the structure shows very little variation in different parts of 
the rachis. The most noticeable features are the large number of resin-canals and the 
entire absence of sclerenchyma. 
