528 
J. G. GROSSENBACHER 
appeared to indicate that the gliding was toward the less lignified 
cells ; but in the cases shown in figures 2 and 4 the matter is different. 
In the instance figured in 2, the ends of the cells curved toward the 
Fig. 6. Longitudinal Sections, showing Gliding Growth. B, elongating phloem 
cell intruding between two neighbors and forcing them apart, as shown at the pits. 
/, elongating xylem cell intruding between and forcing apart two other cells, as 
shown at the pit s. (Figures copied from Neeff's article, Uber Zellumlagerung 
Zeit. fiir Bot. 6: 465-547. 1914.) 
large vessels (a) and (b), while in 4 the curvature was away from the 
bark. It is seen to be in the direction of a vessel (v) that is rather 
remote from the starting point of the long glide. 
General Discussion 
It appears to be an established fact that the Bars of Sanio run 
continuously through certain radial groups of cells in the wood and 
bark; and that such groups probably arose from the divisions under- 
gone by a meristematic cell and its progeny subsequent to the 
origin of the bar, and before the last daughter cell of the group is 
forced from the cambial zone and becomes differentiated into mature 
tissue. The fact that the bars present in the different cells of such a 
