336 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [V, IV
By this time of the year no active lesions were to be seen, and so the investigation
was confined to quiescent and initial lesions only. On the 21st December, 1933,
the writer succeeded in finding microfilariae in a quiescent lesion in a cow at
Tezpur, and after that time these parasites were constantly observed in smears
prepared from a large number of cases in the same district. It is to be stated that
the microfilariae could not be detected in smears prepared from initial lesions,
though a sufficient number of them were examined in the course of the investiga-
tion.
In making smears for microscopical examination at Tezpur the procedure
was to currette away the surface of the sore at a selected spot, and collect tissue
materials from its deeper part. The failure to observe the parasite at Gauhati
in the beginning was due to the fact that smears from the superficial part of the
sore were prepared for examination, while the parasites were situated in the deeper
structures of the sore. By following the technique adopted at Tezpur the writer
has subsequently been able to observe the parasites in all cases of the disease with
quiescent lesions.
An opportunity for collecting pieces of diseased tissue was availed of during
the post-mortem examination of a bullock at the Government Cattle Breeding
Farm, Khanapara, Gauhati. Histological examination of the tissue revealed the
presence of adult worms in sections prepared from it. The parasite was found lying
in the papillary portions of the corium immediately underneath the rete malpighi.
At a later stage of the investigation, attempts were made to recover live parasites
from the lesions, but only a few of them were recovered. On examination they
were found to possess certain affinities with sub-family Setarinae of the family
Filariidae, but the exact identity of the parasites could not be determined due to
lack of a sufficiently large number of specimens for examination.
In July, 1934, when active lesions were available for examination, the writer
was able to isolate microfilariae from these also. Though adult worms have
been isolated from a comparatively few cases of the disease, microfilariae have
been observed in 100 per cent. of the cases with advanced lesions. So far the
disease has been investigated in the districts of Kamrup, Darang, Sylhet, Cachar
and Sibsagar, and in affected areas of all the districts the disease was found always
associated with microfilariae in the lesions. Smears prepared from all the cases
were stained with Leishman's stain which brought out the morphological details
of the parasites quite clearly. The granular body and the empty spaces which
are the essential features of the microfilariae were clearly observed (Plate XXXI).
In smears,embryonated ova (Plate XXX) were found in groups of 4 to any number,
the group being embedded in a cellular matrix composed of plasma cells and lym-
phocytes generally, though eosinophiles have also been observed. In dehaemoglo-
binised smears, however, the microfilariae were found free (Plate XXXI). The
microfilariae showed no motility when observed in wet preparations made of
blood mixed with tissue scrapings.