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Scientific Memoirs by Medical Officers of the Army of India.

tissues it is hard to determine. At certain points in some specimens, however,
continuous penetration of the lamina throughout the greater extent of its thick-
ness by unequivocal algal elements connected with those of the superior sub-
epidermal thallus can be recognised, the peculiar green or yellow colour of the
contents distinguishing the parasitic from the host elements very clearly (Plate
I, fig. 7). It appears that, as a rule, penetration of the deeper portions of
the laminar tissue only occurs at isolated points by means of series of cells
which serve to connect the inferior surface of the superior, subepidermal thallus
with the scattered masses of cells above the inferior epidermis giving origin to
the inferior tufts of fertile filaments.

     We have here to deal with intrusive algal elements which, both as regards
their relation to the host tissues and the effects which they produce on them,
clearly differ greatly from those of Stomatochytrium. The algal elements here
do not occupy normal interspaces in the tissue, but force their way between
normally closely adapted structures breaking up the continuity of the laminar
structure. They produce effects on the tissues of the host not limited to mere
distortion from mechanical pressure, but giving rise to such interference with the
normal process of nutrition as to lead to death, and ultimate disintegration in
masses of tissue in which mere mechanical distortion is entirely absent. The
effects are certainly characteristic of parasitism as distinguished from simple
entophytism. It is impossible to suppose that in this case the nutrition of the
intrusive elements can be carried on without interfering with that of those of the
host. They are not, like those of Stomatochytrium, so superficially situated as
to have a direct relation to the outer world. On the contrary, they are, save
where fertile filaments emerge, buried in dense masses of tissue. Due to their
distribution they must at all events interfere with the nutrition of the host ele-
ments by misappropriation of materials properly destined for the use of the
latter. Whether the interference goes further than this, whether it advances to
the stage of appropriation of organised products developed by the host tissues,
remains uncertain, but the instances in which large masses of the intrusive
elements appear to be almost or totally devoid of chlorophyll and yet in vigorous
growth strongly suggest that such higher parasitism really prevail.

           CALCUTTA;
       The 15th April 1887.