252 Mr Barber, Parasitic Trees in Southern India. 
portions. The nucleus appears as an oval mass of smaller, denser, 
more protoplasmic cells at the distal end of the organ, where it 
applies itself to the body attacked. On either side of the nucleus, 
larger, more permanent parenchymatous cells form the cortex. 
The latter is produced on either side of the foreign body so as to 
clasp it in the form of two cortical folds. 
As growth proceeds, the median part of the nucleus, becoming 
denser, developes into a well-defined gland (Plate II., fig. 1), with 
lumen and duct. The purpose of the gland is presumably the 
outpouring of a dissolving secretion and, from observation of the 
tissues attacked, this secretion appears to be mainly cyto-hydro- 
lytic, starch grains being in many cases more slowly dissolved 
than the cell walls. An examination of the glandular cells shows 
that the secretion is formed beneath the cuticle, and, in good 
sections, a series of parallel curved lines (ghosts) show that suc- 
cessive outpourings have occurred in each cell of the mucilaginous 
substance which fills the lumen of the gland. The secreting cells 
bordering the lumen form a well-marked epithelium-like layer, 
in which the dense protoplasmic contents collect in the lower half 
of the cell cavity, the upper part being full of clear substance 
(Plate II., fig. 1 a). 
When the haustorium meets with a substance difficult to 
penetrate, a fresh mass of meristematic tissue is frequently 
formed at the point of contact, which developes a fresh nucleus 
and fresh cortical folds. The latter grow down on each side 
between the part clasped and the earlier folds, thus detaching 
them and taking their place. Compound haustoria are thus 
formed, which present the appearance of a series of haustoria one 
on top of another, the latest formed one alone being in contact 
with the foreign body. Such compound haustoria are formed, 
especially when the root encountered has thick bark or strong 
sclerotic protective bands, such as characterise the roots of tropical 
Leguminosae, and those of palms, bamboos, &c. The compound 
haustorium may therefore be regarded as indicating a series of 
successive efforts at penetration. Compound haustoria have been 
met with attached to pebbles and, in one case, to the chrysalis of 
a minute Lepidopteron. One haustorium was observed which had 
made five separate attempts to penetrate a refractory particle of 
quartz. The haustoria are freely developed when no other roots 
are present and this, together with the facts just noted, shows 
that no definite organic stimulus is necessary for their formation. 
There is considerable internal pressure in growing haustoria. 
This is caused by the great increase in size of the organs, their 
close contact with the root attacked and the resistance of the 
surrounding particles of soil. This pressure is indicated by the 
appearance, at an early stage of development, of a band of 
