365 
Kendrickia Walkeri, Hook. f. 
occupying an oblique position, surrounded by a mass of parenchyma-cells. 
These have evidently been separated from their neighbours, twisted out of 
position, surrounded, and then left behind by the cells of the advance 
guard of the new ingrowth. 
The material at my disposal contained only one portion of a com- 
paratively old stem (Fig. 17), but from an examination of this it was quite 
evident that the changes in Kendrickia were by no means at an end when 
the parenchymatous communications between the wedges and the pith were 
effected. No formation of secondary cambium in the large-celled paren- 
chyma of the ingrowth was ever observed, but it seemed as if the quiescent 
cambium, lying between the original internal phloem-groups and the axial 
woody ring, had, stimulated apparently by the arrival of the cells of the 
ingrowth, become active once again, and cut off xylem on the one side and 
phloem on the other. Only four such groups were noted, but from lack of 
mature material further developments could not be observed. 
General Comparisons. 
From the naked-eye appearance (Figs. 15, 16, and 17) the stem of 
Kendrickia would seem to resemble rather closely the stem of a climbing 
Bignonia , or one of the Malpighiaceae. In reality, however, the cases are 
very dissimilar. In these plants, at the stage which would resemble 
Figs. 15 and j6, the areas of soft tissue, the so-called furrows of Schenck, 
consist of bast-plates with cambium at their central margins, and result 
from a decreased formation of secondary xylem, with increased production 
of secondary phloem at these several points. Very different is it with 
Kendrickia , where the cambium ring remains complete, is never broken up, 
nor more than slightly deflected towards the pith, and where the ap- 
pearance of furrowing of the wood is due entirely to the difference in 
thickening of the cell- wall in adjoining areas of the secondary xylem- 
elements. The furrow in the one case contains bast, and in the other 
xylem-parenchyma. 
A comparison of the later changes is of great interest. In Tetrapteris> 
one of the Malpighiaceae, the cambium at the inner margin of the furrow, 
after a period of quiescence, again becomes active, and cuts off xylem and 
phloem at the sides of the furrow. The medullary rays of the axial woody 
ring, lying in the prolongation of the furrow, then proceed to stretch and 
divide, and form broad bands of dilated parenchyma-cells, which split the 
woody ring into a definite number of segments. 1 A somewhat similar 
process takes place in the stems of many of the Bignoniaceae. 
Hill 2 points out that in the tuberous portions of the roots of Bignonia 
1 Schenck, Beitrage z. Biol. u. Anat. d. Lianen, Pt. ii, p. 115. 
2 Ann. Bot., vol. xii (1898), p. 323. 
