no Worsdell. — On the Comparative Anatomy of 
As above stated, these plants are parasites % they obtain 
their nourishment, therefore, by means of haustoria , which 
penetrate the living tissues of other plants ; the roots serve, 
not, as in most other plants, for the absorption of water 
and mineral substances from the substratum, but as store- 
houses of nutriment, for the production of the flowering- 
stems, and for the perennation of the plant and the extension 
of its area from year to year. The stimulation to formation 
of a haustorium is caused by direct contact of the root with 
that of the host-plant, which, in this case, is a species of 
Strobilanthes. The external layer of cells at the point of 
contact divides in places, and the cells for some distance on 
either side become elongated radially, while they become 
filled with dense protoplasmic contents, and exhibit con- 
spicuous nuclei ; at the same time, the cortical cells im- 
mediately below this layer divide rapidly in several directions, 
while a few divisions occur in those more deeply situated. 
As a result of this, the initial stage of haustorial formation, 
the cortex becomes considerably bulged out, as seen in 
transverse section (Fig. 21). A few of the cells, on either 
side of the point of contact, grow out into hair-like papillae, 
which possess a thick cell-wall and dark-brown contents with 
a prominent nucleus. These grow towards the host-root. 
The portion of the cortex at the point of contact at length, 
by repeated divisions in the cells, grows out as the haustorium. 
This new organ, by the aid of its external layer, dissolves its 
way by fermentative action into the tissues of the Strobilanth. 
That portion of the root of the parasite around the point 
of penetration becomes applied firmly to the surface of the 
attacked root, the cells in contact being much elongated 
and more or less contorted in shape, with dense contents. 
As the haustorium advances inwards towards the centre of 
the host-root, the effect of its work of absorption of food- 
substances from the living tissues of the host is shown by 
the distinct zone of cortical cells extending from the haus- 
torium to the central cylinder of the parasite, which are 
densely filled with starch-grains (Fig. 22) ; this zone is best 
