134 WorsdelL — On the Comparative Anatomy of 
species in the bilabiate calyx, and in the anterior lip of the 
stigma being oblong, not broadly dilated. 
Summary of Results. 
I may now bring forward the chief results accruing from 
the morphological and anatomical study of these three species. 
The chief factor to be dealt with in these plants, and which 
influences their whole vegetative structure, is their parasitism. 
In one species, as we have seen, this mode of life has had 
a most marked effect, not only on the external form, but also 
on the internal structure of both the root and the stem, both 
having become adapted, chiefly in a retrogressive direction, to 
suit the changed habit and conditions of life of the plant. 
The chief peculiarities in these plants, v r hich may be con- 
sidered as the outcome of their parasitic habit, are the 
following: the branching and anastomising root-system, 
from which the flowering-stems are produced ; the rhizome- 
like character of the root, and the absence of root hairs ; 
the development (in one species) of tubers, from which the 
haustoria and the young lateral roots and stems are produced, 
and which serve as storehouses for the nutrition of the plant ; 
the modified anatomical structure of the cylinder of the root, 
in which the xylem has become reduced and the phloem 
correspondingly developed ; and the reduction of the conduct- 
ing-tissue of the stem, co-related with the absence of foliage 
leaves, which are here replaced by scales. 
The most abnormal and interesting feature occurring in 
these plants is presented by the subterranean portion of 
C. subacaulis especially, which, on investigation, is discovered 
to consist of organs having the character of roots , though 
their morphological nature is well concealed, owing to their 
extreme modification arising from the parasitic habit. 
The tubers , which arise at intervals in the root-system of the 
plant just named, are the most important parts of it, for it is 
from these that the haustoria are chiefly formed, while they 
also act as reservoirs of nutriment for the whole plant. 
The haustorium is interesting as having an exogenous origin, 
