232 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [III, III.

general circulation to certain parts of the body, where they are arrested owing to
previous thrombus formation, and not deposited on existing wounds by the fly.

Turning now to the specific identity of the Habronema responsible for Bursati in
India, H. muscae appears to be the most probable. It may be noted that in France
and Australia, H. megastoma is incriminated as the causal agent of Summer Sores
and Swamp Cancer, and that in Brazil, Margarinos Torres [1923] considers " H
muscae is the most important and perhaps the only cause of the disease ", and Van
Saceghem [1917] believes the same to be true in Zambi in the Congo. That the
measurements and character of the anterior end of the larvae, as seen in sections of
the skin and again in sections of the prepuce lesion conforms to those of H. muscae
has been mentioned earlier in this article. The occurrence of the same species of
the worm to the exclusion of other species in the stomach of a case, which showed
both pulmonary and cutaneous habronemiasis, appears to be more than a mere
coincidence. The experience in India would therefore support that of the Brazilian
worker and of Van Saceghem [1917 ].

In regard to the probable intermediaries, certain native flies, six muscid and
one sarcophagid of Queensland [Johnston, 1920], Drosophilid flies in Ceylon
[ Crawford, 1926 ], have been incriminated in addition to the usual Musca domestica
and Stomaxys calcitrans and recently Patton [ 1932 ] has stated : " Musca crassiros-
tris is a probable transmitter of Habronema in India, for I have found these nema-
todes developing in it ". In addition to being related to " special districts " and
" special seasons ", Bursati has been called a disease of ''special circumstances"
by Burke [ 1881 ], and though the precise factors are as yet imperfectly understood,
the occurrence of particular species of Habronema and of the appropriate flies in
the same locality now seem indispensable to the production of Bursati. The fact
that the sores, after having manifested considerable resistance to treatment, tend
to disappear spontaneously at the approach of the winter indicates that the supply
of the larvae is no longer continued. That a close relationship must exist between
the cycle of evolution of the bursati Habronema and the life-history of its inter-
mediate host is obvious from the work of Ransom [1913, Hill, 1920 ] and others:
and until the evolutionary stages of the worm in relation to the fly in question have
been worked out, month by month, the factors responsible for the bursati, season
and districts, will not be understood. A scheme of evolution has been given by
Roubaud and Descazeaux [ 1921 ], but as far as the writer is aware, this has still
to be confirmed. As a result of histological studies upon sections of H. megostoma
tumours, from about 20 cases, collected at different times during a number of
years, the author could obtain no proof for the view originally advanced by Des-