J. F. SHIRLAW                                  149

of mycotic pneumonia simulating the lesions of contagious bovine pleuro-
pneumonia has been encountered in sporadic form in cattle maintained at
Mukteswar. The finding of what appears a true fungus in the lesions of the
disease in Assam correlates the observations on the disease in cattle at Muktes-
war. It has been reported from Assam that the peculiar type of bovine pleuro-
pneumonia observed occurs in sporadic form. It has already been noted that
bovine pleuro-pneumonia is not a sporadic disease.

It would be premature, at this early stage of the investigation, to attempt
to explain the etiology of the disease in Assam ; only two sets of specimens
have been examined, but it is significant that, in both cases, the type of lesion
appears peculiar to the disease and is one which could be readily explained on
the basis of infection by a fungus, as in the cases observed at Mukteswar.
The essential origin is bronchiogenic and on the mucosa of the bronchi are
seen masses of spores which penetrate through the bronchial coats into the
interstitial tissue. Hæmorrhage of the small vessels of the bronchial wall is
apparent and a suitable explanation of the essential lesions of the peculiar type
of pneumonia described is that the spores enter the ruptured venules of the
mucous coat and thence make their way by the bronchial veins to the right
heart whence they return by the pulmonary arteries, the terminal branches of
which, being an end arterial system, they occlude with the development of the
lesions described. The fact that only one side of the lung may be affected is
explained by the observation that each lung is supplied with its own special
and anatomically different bronchial vascular system.

In mycotic pneumonia, Folger [1926] postulates a blood stream spread
of the spores, but it is contended by the writer that this is not necessary in view
of the anatomical distribution and peculiarities of the bronchial vascular
system. The spores developing in the lung in a case of mycotic pneumonia
can, and probably do, return to the lung by the branches of the pulmonary-
artery. The blood stream spread theory is hardly tenable in view of the fact
that no observations are available of the effects produced in the end arterial
system by circulating spores. If spores were circulating in the blood, a more
general thrombosis of the end arterial system, with the development of obvious
infarcts in the special organs supplied, would be of certain occurrence.

This not entirely irrelevant digression in pathology indicates the need
for continuous and intensive investigation on pneumonia of bovines in
India.

                                        CONCLUSION

There is no evidence that contagious bovine pleuro-pneumonia exists,
or has ever existed, in British India.