20 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [ III, I
is now known that the lungs may be the seat of lesions caused by the migration of
the larvæ of Ascaris megalocephala [Hobmaier, 1925], of Strongyles [Olt, 1910 and
Theiler, 1918] and of Habronema [Dieulouard, 1927], but the possibility of Schisto-
somes playing a role in the production of lung lesions, the importance of which in
human affections has been emphasised by Turner [1909], has not so far been con-
sidered in Veterinary Pathology. During the investigation under report, lesions on
the pleura and the lung parenchyma have been detected quite frequently. Patches
of chronic pleuritis, gram-sized sub-pleural nodules (Plate 1, specimen 1481) or
highly calcareous, nodular aggregations on the pleura (Plate I, specimen 750-A)
have been seen. The anterior lobes of the lung may be united along their borders.
Lung parenchyma may show patches of consolidation, with organised and very sharp-
ly defined nodules of rounded shape distributed throughout. Their size may reach
that of a green pea (Plate I, specimen 1562) and they never show any caseous
softening. Examined under the microscope, the lung shows the same characteris-
tic features in the organised nodules, as seen in the other organs. The nodules
consist of an inner area of degenerated cell debris with or without calcification,
surrounded by a more or less strong fibrous fortification (Plate II, Fig. 3). The
nodules appear to form in the vessels of the intervesicular septa and from the
smallest to the largest the nodules maintain a perfectly rounded shape in the
different stages of fibrosis. A chronic catarrhal type of pneumonia, in which the
air vesicles are seen to contain eosinophiles and some undifferentiated coagulum
probably serum, may affect only portions of the parenchyma or may involve the
whole organ. In passing, it may be mentioned here that the lung lesions of a ne-
matode infection can be distinguished without much difficulty from the specific
lesions of bilharziosis in the majority of instances. The former is usually a bron-
chial or peribronchial affection and the lesion covers a much larger area. This is
understandable since the causative agent is a worm larva, which according to
Theiler [1918], reaches its place by way of the bronchi. In this connection, it will
be remembered that a reference has been made already in the introductory remarks
concerning the two types of lesions of the lungs encountered by Lingard [1905]. He
noticed that the larger variety of lung lesions was less frequent and this finding
is in accord with those of the writer. Nematode lesions are generally few and they
are seldom organised when small. Even in a larger lesion, the concentric arrange-
ment is not so well developed, for there may be only a few rings of irregularly
circular connective tissue. The bilharzial lesions, on the other hand, are generally
uniformly distributed, being formed as a result of an embolism in the capillaries of
the interalveolar septa. As the lesion is generally formed around a single Schisto-
some ovum in a capillary, the resulting nodule or the degenerated eosinophile debris
in its centre is much smaller and yet the rings of fibrosis are well developed.