Jeffrey and Torrey . — Transitional Herbaceous Dicotyledons . 229 
depression of the cylinder is obviously subtended externally by unmodified 
wood. The truth of this statement is confirmed by the inspection of Fig. 4, 
PI. XI, which represents a tangential section through the foliar trace in its 
outward course through the wood. Above the trace lies a dark patch, the 
parenchyma of the leaf-gap, which is continuous internally with the medulla. 
The narrow pointed elements, abutting on the lower border of the parenchy- 
matous tissues of the leaf-gap are the tracheary elements of the foliar trace. 
Below the leaf-trace neither foliar ray nor any appreciable aggregation of 
the ordinary rays of the wood can be distinguished. It will be clear to the 
reader that nothing of the nature of a foliar ray is present in relation to the 
leaf-trace in the genus Tilia . Turning to the genus Abutilon , cited and 
figured by our authors in support of their view, we find in Fig. 5 a total 
transverse section of a year-old stem of Abutilon species. The plane of 
section is the same as in Tilia, namely, slightly below the node. The 
topography exhibited is, however, quite different, for here there are distinct 
parenchymatous interruptions in the continuity of the woody cylinder, three 
in number, corresponding to the three foliar traces entering the stem at the 
node. In Fig. 6, PI. XI, one of these parenchymatous interruptions, or, as we 
prefer to call them, foliar rays, is shown under a higher degree of magnifi- 
cation. The organization of the structure in question obviously is entirely 
parenchymatous, and, contrary to the confident assertion of our critics, it is 
subtended internally by a small leaf-trace. Moreover, the node chosen for 
illustration belongs to the aerial stem, so that their contentions in every 
respect are proved erroneous on the basis of one of the genera chosen by 
them to illustrate the superior accuracy of their knowledge of the anatomy 
of Dicotyledonous herbs. Fig. 3, PI. XI, illustrates the tangential aspect of 
the foliar ray in Abutilon . The leaf-trace is seen to be surrounded on all 
sides by copious parenchyma, constituting for the most part the substance 
of the foliar ray. A small portion of the parenchyma on the upper surface 
of the leaf-trace must, however, be conceded to the foliar gap. A very 
significant organization is presented by the lower region of the foliar ray. 
It will be observed that it passes gradually into the substance of the wood, 
and accompanying this transition is the progressive transformation of 
parenchymatous elements into fibres. This condition clearly indicates the 
fibrous origin of a considerable portion of the foliar ray. The rest of its 
substance must be regarded as composed of the fused normal rays of the 
wood. A very instructive comparison is that of Figs. 1 and 5, of Figs. 2 
and 6, and of Figs. 3 and 4. In each case can be noted the relations of the 
leaf-trace to the organization of the cylinder in woody and herbaceous stems 
of close affinities. It probably will be quite clear to the reader that there is 
a distinct and interesting difference of organization between Tilia and 
Abutilon , which is most strikingly expressed in the development of specially 
large storage rays in the case of the latter, in relation to the entering traces 
