536 PROCEEDINGS OF THE AMERICAN ACADEMY. 



longitudinal stripes are to be noticed particularly to the right of the 

 center of the figure. These represent resiniferous parenchyma. 

 Figure d, Plate 2, shows a portion of the last figure more highly magni- 

 fied, to make clear the transverse partitions separating the resiniferous 

 elements from one another. Figure h, Plate 2, shows the same wood 

 in transverse section, the dark spots indicating the presence of the 

 resiniferous cells. Figure c, Plate 2, shows a section of the same wood 

 near the pith, making it clear that we have to do with the stem w^ood of 

 an extinct araucarian conifer. The resiniferous elements can be seen 

 as in the preceding figure scattered throughout the wood. The writer 

 has had the opportunity of examining a number of araucarian woods 

 from the Raritan Cretaceous of the Eastern United States and has 

 found in all true Araucarioxyla an abundance of wood parenchyma. 

 In this respect they present a marked contrast to the normal stem 

 wood of the living Agathis and Araucaria, although resembling them 

 to a striking degree in other respects. 



Let us now turn our attention to the conservative organs of the 

 living genera. Figure e, Plate 2, illustrates the structure of an old 

 root of Agathis anstralis, near the center. It is to be observed that 

 the wood is thickly sown with parenchyma cells. These, it may be 

 added are most abundant near the center of the root and die out pro- 

 gressively as the outer annual rings of the older root are reached, 

 unless recalled by injury, as is noted below. Figure a, Plate 3, shows 

 a longitudinal section of the same root, making it clear that we have 

 really to do with resin cells and not merely with tracheids filled with a 

 resinous or mucilaginous contents such as are not infrequent in coni- 

 ferous woods of varied affinities. Resin cells are extremely common 

 in the first formed annual rings of the root in the genus Agathis and 

 likewise occur to a less degree in the root organs of Araucaria. In 

 certain species of Agathis, they likewise are found in the first annual 

 ring of the stcvi. This condition may be illustrated by A. australis 

 and A. Bidwillii, which represent as nearly as possible the extremes 

 of affinity within the genus. Figure b, Plate 3, illustrates the mode 

 of occurrence of parenchyma in the first year's growth of A. Bidwillii. 

 The dark spots are parenchyma cells. Figure c, Plate 3, shows a 

 longitudinal section of the same species. On the left is seen the 

 protoxylem and a little to the right of the center, a row of parenchyma- 

 tous elements, still retaining their protoplasmic contents. Figure d, 

 Plate 3, shows the same conditions in the first annual ring of A. aus- 

 tralis. Here the parenchyma tends to occupy the face of the summer 

 wood, in the first yearly increment, thus resembling the conditions 



