14 STUDIES IN ROOT-PARASITISM. 
crushed, while those within are obviously compressed and show 
undulations on their radial walls. The outer part of the col- 
lapsed layer is usually the oldest and, in late stages, becomes 
yellow and homogeneous, while the inner parts are still white 
and show their manner of origin from flattened cells. This 
decay of the outer part of the collapsed layers is not infrequent, 
and the application of staining reagents shows that a change 
in substance is taking place and that the outer parts are always 
more altered than the inner. 
In conclusion. the smail part played by the collapsed 
layers and the cortex generally in old haustoria reminds some- 
what of what takes place in Buckleya Quadriala according to 
Kusano.* Here cork continues to be formed at increasing 
depths in the cortex, until ultimately almost the whole of cor- 
tex including the collapsed layers is thrown off. 
10. Yellowiny of the tissues.—Masses of yellow, transparent 
substance are not uncommon in the haustoria of Cansjera 
Rheedii. These are found not only in the vascular system, as 
in the interrupted zone and the older secondary wood, but in 
many parts of the nucleus and cortex, which habitually undergo 
disintegration. 
In young haustoria which for some reason have been 
arrested in their growth, large lacune are not infrequent (Plate 
III, fig. 3). These are lined with yellow, transparent sub- 
stance, formed by the breaking down of the cells whose places 
the lacune occupy. 
In cases where the cortical folds have failed to grasp the 
object attacked and are thus brought into contact with the 
sides of the sucker, the space between these parts is filled with 
a similar yellow substance. This is also not uncommon in San- 
talum (Sant. I, figs. 14 and 15, gl). The lumen of the gland, 
again, after it has ceased its activity, is usually filled with 
vellow substance. 
* Kusano, S.. Studies in the Parasitism of Bukleya Quadriala B, et H.. 2 Santalaceous 
Parasite, ete. Journ, Coll. Sc. Imp. Univ. Tokyo, XVII, No, 10, 1902, 
