MR. W. C. WOESDELL ON " TEANSFUSIOX-TISSUE." 311 



surfaces, it can be seen that the transfusion-tissue is bordered, on the side away from the 

 bundle, by a single layer of parenchyma -cells similar in shape to its own tracheides. 

 Immediately abutting on these, however, by their expanded ends are to be seen strands 

 of lignified elements wliich, starting from this region, run out through the mesophyll to 

 the margin of the leaf (fig. 16). In arrangement, shape, and general appearance they 

 resemble extremely the strands of "accessory transfusion-tissue" in Cycas. But the 

 individual elements present a remarkable difference from those of the "accessory 

 transfusion-tissue " in Cycas, from the fact that they possess narrow, slit-like simple pits 

 in their walls without the remotest trace of any border. From the thickness and 

 consistence of their walls, the simple pits, and the scattered arrangement of these latter, 

 they have very much more the appearance of stone-cells than of traclieides, and it is 

 possible that they are analogous to the tracheides occupying the same position in 

 Cycas only in so far as the mechanical function of strengthening the broad lamina of 

 the leaf is concerned, and that they therefore do not possess in any way a conducting 

 function. 



Podocarpus Totara, G. Benn. — In the much shorter and narrower leaf of this species 

 it is interesting to note the complete absence of this tissue in the leaf. Here the central 

 mesophyll-cells are elongated in the direction of the margin of the leaf, but are thin- 

 walled and unpitted. I was able to determine, however, the presence of a very slight 

 lignification of their walls. 



P. alpina, B. Br. — In the still smaller and evidently much reduced leaf of this species 

 the same entire absence of this tissue was to be seen. Here and there, however, in the 

 central region of the leaf, and occupying the same position as the thick-walled, pitted 

 elements of P. chilina, Bich., occurred one or two large stone-cells. One of these 

 abutted directly, by its narrower end, on the cells immediately adjoining the normal 

 transfusion-tissue. Another was seen to be in intimate connection with an assimilating 

 cell of the parenchyma. Except for their greater diameter, these cells looked exactly 

 like the elements above described in P. chilina, Bich. I am tempted to regard them as 

 a relic and last vestige of the well-developed tissue as seen in P. chilina, Bich., the 

 latter, owing to the great reduction of the leaf in breadth, as well as in length (probably 

 from its exposed habitat on the mountains), having become no longer necessary. As 

 regards the structure of the leaf of P. Totara, G. Benn., it may possibly also be a 

 reduction from the type of P. chilina, Bich., but it is impossible to be certain of this. 

 The stone-cells, in the two species examined, are devoid of contents. 



In this genus there appeared no sign of centripetal xylem attached to the bundle, as 

 in other Taxinese. 



Araucaria excelsa, B. Br.— Having at my disposal a seedling with four cotyledons, I 

 was able to thoroughly investigate the structure of the latter. Each cotyledon is oblong 

 in shape, with a broad lamina traversed by about six vascular bundles and a number of 

 hypodermal resin-canals. It is denticulate at the apex. A transverse section showed 



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