53
(a) Of the mouth :—These inelude all breaches of the surface, by which a
solution of continuity in the tissues has been brought about, whether
in the mouth or on the lips ; and caused by the bit, or more especially in
this country, in consequence of the animals having coarse fodder to
eat, as jawári (Sorghum Vulgare) and spear grass.
(b) Of the œsophagus :—Under this heading may be included wounds in
the epithelium of the oesophagus caused by the "spiroptera scutata."
(c) Of the stomach :—The tumours found in the right sac of the stomach,
with orifices on their summits, leading down into their interiors are
the nests of the " spiroptera megastoma" Too much stress cannot be
laid upon the fact, that these parasites (by the pathological condition
they produce) are a source of real danger to the animal which they
infest, and especially to animals, which have their habitats in a part of
the country known to be within the geographical range of Surra.
In the left sac, the alveoli of insertion of the gastrophilus equi, and
the gastrophilus hœmorrhoidalis.
(d) Of the small intestine :—In the jejunum and ileum, large numbers of
cestodes and nematodes may be found ; these must continually wound
the surface of the mucous membrane by their bites.
(e) Of the. cæcum and colon :—These portions of the intestinal tract may be
the seat of enormous numbers of parasites, of which the armed Scl-
erostomes (Sol : equinum, Müller, or Strongylus armatus, Rüd.) do a
considerable amount of damage, by producing wounds on the inner
surface of the intestine; the young undergo development under the
mucous membrane, and when they escape, leave small holes leading
into the tumours.
B.—EXCITING CAUSES.
Although it has not. been absolutely proved, that the Trypanosoma Evansi
is the ' vera causa' of Surra, owing to the fact that it has not been separated,
although numerous attempts have been made, and pure cultivations of it used
for inoculation in the production of the disease ; nevertheless all our experi-
ments point to the probability of its being so. The following facts go to show
the intimate connection which exists between the organism and the disease.
1. No case of " Surra " naturally contracted has been observed, in which
the " Trypanosoma Evansi" has been absent, and all previous authenticated cases,
investigated by such observers as Evans, Steele, Pottinger Gunn and Rimington
tend to confirm this.
2. In all cases of the inoculated disease the organism has been present,
and has comported itself in a similar manner to that which has been observed
in naturally acquired cases.
3. By passing the hæmatozoon through the organisms of various animals
and after a considerable time bringing it back to the horse ; fatal Surra with all
its distinctive characters has again been produced, without the hæmatozoon
being absent in a single instance.
4. Serum of blood swarming with the organism, after having been passed
through a porcelain filter, and thus deprived of any recognizable form of the
hæmatozoon, does not produce " Surra " ; nor is the organism ever found in the
blood of the inoculated animal under these circumstances.
In addition to this we have the undoubted influence which the presence or
absence of the " Trypanosoma" has upon the course of the disease, dividing it
into its various stages, viz., paroxysms and intermissions.
It may be generally accepted that the appearance of the organism in the
blood is quickly followed by a rise in the temperature, and as a rule its disap-
pearance is soon followed by a corresponding fall. During the presence of the
organism in the blood all the phenomena of a paroxysm of ' Surra' appear, whilst
after its disappearance there is a very marked diminution of the severity of the
symptoms. And so much is this the case, that in some instances at the com-
mencement of an attack, an animal has been sent to work after the first-
paroxysm, being apparently well.
B 1086-14