12 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [ III, I

Numerous minute greyish white or chalky white nodules resembling miliary
tubercles can be seen immediately beneath the transparent capsule (Plate I,
specimen Nos. 1532 and 562 iii). These nodules are more or less calcified, as large
as a sago grain, but rarely, they may attain the size of a split pea. Palpation of
the surface gives a slightly irregular feel, but the organ is never characteristically
' hobnailed ' even in an extreme case. Occasionally several advanced nodules may
be seen crowded together over the surface of the organ (Plate I, specimen
No. 750-B). In rare cases elevated nodular areas of induration may also be seen
protruding in a like manner (Plate I, specimen No. 993). Degenerative
softening of the nodules has never been seen to be associated with the condition.
The organ cuts with a gritty or cartilaginous feel, and then will be seen many more
minute nodules which are red in the early stages but vary from greyish or greyish
white to pearl white in colour as the disease advances (Plate I, specimen
No. 1558 left). If an individual nodule is removed with the point of a knife and
a caustic potash preparation of the crushed material be examined under the
microscope one or two oval, spined eggs may be seen. The cut surfaces present
a coarse net-work of grey or greyish white bands of fibrous tissue of varying breadth,
enclosing in each mesh rounded islets of yellow or yellowish brown hepatic tissue.
When the disease has advanced further, the linear tracts of connective tissue become
so thickened and prominent as to present a marbled appearance or a " claypipe
stem " picture due to thickened bile ducts as delineated by Symmers [1903] in cases
of Egyptian Schistosomiasis (caused by S. mansoni). The liver may be so densely
packed with the nodules in varying stages of calcification and organisation that
very little true liver tissue can be recognised by the naked eye. The old nodules
may be so highly calcified that they readily become enucleated on the slightest dis-
turbance with the knife (Plate II, Fig. 1).

The development of the lesion in this equine affection takes place in the same
manner as in the case of other forms of schistosomiasis. There are certain
differences, of course, but they may be ascribed to the different degrees of patho-
genicity of the species of the parasite concerned and probably also due to the
varying powers of resistance possessed by the invaded equine tissues. The essential
lesion of the disease is a nodulated cirrhosis, practically restricted to the portal
tract in the initial stage (Plate III, Fig. 4). The nodule in its earliest stage
is mainly cellular in character, being composed of a heavy accumulation of mono-
nuclear neutrophile cells and rare polymorphonuclears which again are loosely
surrounded by a few delicate fibrils of connective tissue (Plate III, Fig. 2).
With regard to the origin of these fibrils careful examination of sections has shown
that they are merely the normal supporting tissue which has become arranged
around the irritant in order that it may be phagocytised in situ. The offending