Medical Officers of the Army of India.
3
details, as to do so not only should I have to repeat much of what I have
recently written on the subject of Dochmius duodenalis, but, after all, beyond a
few measurements, no descriptions of organisms such as these can equal fairly
executed plates, and several drawings of various stages of the free stage will be
found appended to this paper, which, being made with the camera lucida, can be
vouched for, at least as to accuracy of outline.
Considering that ordinary grasses and other forage plants form the habitat
of the Rhabdites, the method by which they gain access to the intestinal canal
of herbiverous animals is perfectly obvious, as the worms cannot fail to be
swallowed along with the infested plants. Once the embryos have so invaded a
suitable host their remaining life-history is already fairly well known, and is
described in some detail in Cobbold's "Parasites," page 374, et seq.1 A s t h e r e i n
described, there can be no doubt that the worms, as the first act of their parasitic
life, bore into, and encyst themselves in, the intestinal submucosa, and there
acquire the peculiar four-spined mouth armature, and undergo the initial stages
leading up to sexual maturity.
Cobbold (1879) states, on the authority of Leuckart, that these cysts are
limited to the cœcum and colon, a mistake natural enough, as the latter authority
had had only a single opportunity of examining a case; but, as a matter of fact,
they may also be frequently found encysted in enormous numbers in the walls
of the stomach, and, even when not found there at the time of one's examination,
plain traces of their previous presence may be met with in nearly every case in
which they are at all abundant in the lower bowel. These lesions consist in
cicatricial changes marking the site of the deserted cysts, and vary in character
according to the length of time that has elapsed since they were occupied.
Immediately after the worms have escaped, the cysts will be found to be filled
with fresh blood clot, and subsequently, as the clot decolourises and shrinks, they
become little nodules of caseous-looking matter, surrounded by a zone of in-
filtrated tissue. Finally the contained mass becomes very small, and may
calcify, but the infiltrated zone remains for a long time as a thickened nodule,
of almost cartilaginous consistency, feeling much like an inbedded small shot.
Where, as is often the case, the scars of the deserted cysts are packed closely
together, a mammillated appearance results, together with a general thickening
of the walls of the organ, which is extremely characteristic, and, once seen asso-
ciated with recently escaped worms, is easily recognised as a sequel to their
residence, even when no worms , either free or encysted, are to be found in the
crgan at the time of examination.
Sections of the affected organ showed that the functional efficiency of the
often large areas of its surface affected must be almost abolished; for a large
1
Vide also "Description of Strongylus Arnfield" (Cobb.) with observations on Strongylus tetracanthus
by T. Spencer Cobbold in Trans Lin. Soc. 1886, pp. 284—93. On page 291 will be found a good account of
the bibliography of the species.