252 Holmes . — A Contribution to the Study of 
Anatomy. 
In a transverse section of the internode of the Sycamore stem, the 
wood has a fairly uniform appearance. At the edge of the pith, character- 
istically six-sided in shape, are six conspicuous leaf-trace bundles, containing 
spiral vessels, with smaller bundles between these. The bundles consist of 
several rows of vessels close together, separated from the thin-walled empty 
pith cells by a layer of thicker- walled parenchyma filled with starch. In the 
smallest sections there is little else in the xylem beyond these bundles, 
which are separated by medullary rays several rows .of cells in width. 
These primary rays are distinguishable in the larger sections, traversing the 
