352 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [ IV, IV.
tion are partly absorbed or removed. When the amount of this is more
than can be conveniently disposed of, degenerative changes in the overlying epi-
thelium leads to the formation of ulcers by sloughing. Blood is then easily lost
from the widely-open sub-epithelial vessels, and haematuria manifests itself. If the
parasitic incitants have been removed with the slough and haemorrhage, and a fresh
batch of parasites are not present in the immediate vicinity, organisation of the
broken epithelium commences. Clots are first formed on the raw surfaces and local
capillary thrombosis may take place. Extravasation of blood ceases and haematu-
ria disappears for the time being. The seat of attempted cicatrisation remains a
weakened spot, and further progress of the recuperative process may be undermined
by the intervention of a fresh batch of the parasites. Even if the obliterating clots
or thrombi were to persist and the lesion were to be completely resolved, fresh lesions
appear elsewhere with the reappearance of haematuria. The disease thus obtains a
foothold, and tends to become chronic, and the diverse types of lesions, known to
characterise the disease, manifest themselves. The lining epithelium of the bladder
may still appear to be in tact in the major part, but depressed ulcers of small size with
raised edges, or even coalesced patches of ulceration are to be seen. Generally these
areas of ulceration are superficial and do not extend much below the submucosal layer,
but deep ulceration may at times be encountered as well. Immediately under the
epithelium and extending only a relatively short distance into the deeper tissues are
blood cavities and channels of various sizes and shapes (Plate XXII, Fig. 1). The
connective tissue stroma, which supports these extremely vascular or haemorrhoidal
areas, appears to have undergone some hyperplastic changes. Apart from the
several scattered points where the denuded areas of mucous membrane are in the
process of cicatrisation, one notices a proliferation and thickening of the epithelial
lining. Obviously the series of changes through which the affected mucosa passes
must depend upon the severity of the traumatic injury or irritation, and also upon the
chronicity of the case. In such areas of the mucosa, where the traumatic influences
have not directly operated, or where they have not been unusally severe, the intact
epithelium has to adapt itself to the mild irritations to which it is being continually
subjected from time to time. The bladder tissues attempt to adjust themselves to
the changed circumstances by the production of branching cauliflower-like tassels
of soft papillomatous growths. The character of the epithelium of the bladder is
maintained over these growths, and branches of blood vessels are carried into each
prolongation. A few pyriform mucoid cysts are formed since the escape of the
secretion of the glands of the bladder is obstructed (Plate XIX, Fig. 1).
The fundamental lesions of the disease are however formed in the small and
large-sized vessels, which show definite reactions within and around themselves,
irrespective of their situation in the thickness of the bladder wall. The submu-