10 STUDIES IN ROOT-PARASITISM. 
As already noted, the cells of the nucleus are elongated in a 
direction at right angles to those immediately above them, and 
the latter are now considerably crushed by the nuclear growth. 
The inner cortex is seen to have separated into two dis- 
tinct parts. In the outer, the cells are more or less isodia- 
metrical and filled with starch (6), while, in the inner, they are 
free from starch, have evident, nucleated protoplasm and are 
elongated in the direction of the sucker (c), This division of 
the inner cortex into two parts, although sometimes very clearly 
shown, is not always very definite. It calls to mind very 
forcibly the arrangement of tissues in the penetrating hausto- 
rium of Olax scandens (Olax, Plate VIII). In the latter case, 
however, the inner, elongating cells belong to the nucleus and 
the outer, starch-laden cells to the cortex. The sucker in Olax 
is formed entirely of nuclear tissue, whereas in Cansjera, as 
in Santalum, the sucker is formed chiefly of nucleus, but certain 
of the cortical cells take part, becoming greatly elongated and 
entering the split in the host’s bark. 
The sucker has reached the host’s wood and is spreading 
along the cambial line on each side, thus becoming lobed. 
There is no trace of a former ‘‘ gland,” asin Plates III and IV, 
showing that the formation of this structure is not necessary 
for penetration. (See however para. 5.) 
8. In Plate V, fig. 2, is shown a drawing of a mature 
haustorium penetrating a root of Santalum album. The main 
difference from the preceding stage lies in the development 
of the vascular system which is now fully formed. In the tran- 
sitional region two strands are seen, interrupted at intervals 
by broad medullary rays and separated from the surrounding 
tissues by a distinctly marked endodermis (e). A well devel- 
oped interrupted zone (7. z.) is seen at the top of the vascular 
loop, Where the transitional region joins the haustorium proper. 
selow the interrupted zone the vascular loop is well defined, 
curving round to become a pair of strands in the haustorial 
axis, here without any trace of medullary rays. Two 
