34 STUDIES IN ROOT-PARASITISM. 
of peculiar appearance occur, always accompanied by long rows of 
square cells with single crystals. We may term these “ fibro- 
crystal” groups and their form is seen in Plate X, figures 4 a—f. 
These fibro-crystal masses are frequently found in the transitional 
region of the haustorium but do not (with the exception to be 
mentioned below) appear lower down than the middle of the 
vascular loop. 
Although there is no distinct endodermis visible in the 
Olax roots examined, many sections show in the upper parts of 
the transitional region isolated brown cells of great distinctness, 
their position being in general outside the bast. It is not possible 
to connect these cells with the endodermis, and all that can be said 
is that they occur in the endodermal region. They are traceable 
from the mother root into the transitional region and, as might 
be expected, the outer collapsed layer is seen frequently to be in 
direct continuation with them. They are not found lower down 
than the middle of the vascular loop. 
Cork is a constant feature outside the haustorium, being 
much more commonly found than in sandal haustoria. It usually 
ceases at the ends of the cortical folds, but, in not a few cases, 
has been traced inside the latter as far as the upper ends of the 
cortical wings of the host’s root. In one or two cases it has 
been met with further in, aborted sucker lobes are seen sometimes 
to be surrounded by it and, in one case, the whole sucker has 
been cut off by its own cork formed in thick layers. 
17. The relation between haustorium and host need not be 
dealt with so fully as it has been in Santalum. To do so would 
entail much repetition. An attempt is rather made to compare 
the haustoria of Olax with those of Santalum in their action on 
the root attacked. 
Penetration follows closely the lines indicated in Santalwm. 
The sucker is tongue-like at the commencement, excepting where 
very dense bands of sclerenchymatous cells bar its way. This 
form is retained in certain roots where the tissues are soft and 
watery, as in Boerhaavia repens, where a broad tongue passes 
