C. A. BARBER. 19 
largely dependent on the dissolving action of the glandular secre- 
tion. In Santalum we saw that penetration could be effected 
without this organ and that, if the first attempt proved unsuc- 
cessful, the axial tissues next to the host were able to, so to 
speak, reconstruct the nucleus again and again, each time also 
producing a new pair of clasping folds. A compound haustorium 
was thus produced (Santalum, Part I, Plate V). There is only 
one nucleus and one pair of folds in Olax. Its haustorium 
is never compound. The reason for this is not far to seek. In 
the first place, the gland is exceedingly large and takes up the 
whole of the lower part of the nuclear meristematic tissues ; and 
the tissues of the cortex immediately adjoining are, as we ee 
seen, cleared of all their contents and, when the gland is mature, 
rapidly become moribund. In the second place, it is probable 
that the gland isa much more permanent structure than that in 
Santalum, and the ‘‘cap” in the upper part continues to supply 
cells which pour out their secretion long after the lower part is 
completely disorganized. One reason for assuming this long 
continued activity of the gland is the frequency with which the 
mature gland is met with in the sections. While such stages as 
are shown on Plate IV, figs. 1—3, are rarely met with, mature 
glands such as that on Plate V are quite common—indicating, I 
think, that the gland continues in this active stage for a consider- 
able period, while it passes through the preliminary stages quickly. 
The need for secondary nuclei and cortical folds is not, therefore, 
felt by the haustorium in Olaz and, if it were, there is no meris- 
tematic tissue left near the host’s root which could produce them. 
The figure on Plate VI appears to represent a very late 
stage of the gland: the whole of the lower part has been crushed, 
and the cap is still composed of many layers of secreting cells. 
There is some probability that the haustorium would have 
succeeded in entering this root, for a minute crack has appeared 
in the host’s bark in the middle line and certain of the cells of 
the haustorium are projecting into it. 
There are, however, other points of interest to be noted 
in the haustorium shown on this and the preceding plates. In 
