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Regarding the general conditions of this locality during the unhealthy time of the year,
Adams says: " It is difficult to imagine, the atmosphere is surcharged with moisture arising
from the water logged-soil, and loaded with the products of decaying vegetation, which gives a
sickly smell to the whole place
.....As would be expected at this season,malarious fever is
very general, and the mortality amongst the population is excessive." The last three months
of the year are fine, and Karnal is possessed of an excessively pleasant cold season. Now it
will be noticed, on reference to Table No. II, that it is during the intense heat of April,
May and the greater part or the whole of the rainy season that the Filaria is never observed,
but its presence was, in 97 per cent. of the cases recorded, entirely restricted to the cool and
cold months, October—February, inclusive.
Length of time stationed in the locality before being affected with Filaria Oculi.
Of the 51 cases at Karnal, 43 were country-bred and 8 Australians. The average period,
which elapsed between the date of purchase or birth and the admission for Filaria Oculi, in
the former was 454 days or 15 months, and in the case of Australians 334 days or 11 months
and 4 days.
It might be put forward that, at the time of purchase, some of the animals had in
their systems the ova of the Filaria; this, of course, it is impossible to contravert, except by
the evidence at hand. In the first place, we are fortunate to have three cases to bring for-
ward, viz., Nos. 7, 25 and 36, which were born and reared in the Dep6t, never having been
removed from the estate up to the time of admission to hospital. And from these we see
that the first animal showed ' worm in the eye ' at the age of 2 years and 7 months, the
second at 3 years and 9 months and the third after 9 months. But we have no evidence to
show that all three were submitted to the same conditions, viz., inmates of the same paddocks
and drank the same water. Evidently case No. 36 is the most important for our considera-
tion. This animal was born at the beginning of March 1895, and the Filaria was noticed on
the 5th of December of the same year. Consequently this animal had only lived through
one hot and one rainy season at Karnal before contracting the affection of the eye.
Again some ten of the purchased country-bred horses (Nos. 14, 32, 6, 31, 35, 8, 37, 1,
9, 3) showed the affection after a residence at Karnal varying from six to nine months; but
in all these instances the period included more or less of the hot and all the rainy season.
Consequently we may ask which season is to blame ? Is it the dry when all the ponds are
low owing to evaporation and concentration of the water exists, together with an increased
quantity of animal life, or is it the wet ? On reference to Tables II and III, we may
observe that during the year of heaviest rainfall, viz., 1894, with 45.28 inches, there were 17
cases of Filaria Oculi, and during 1895, with 35.08 inches, 13 cases : but, against this, we
see that in 1892, when 38.27 inches of rain fell, only 3 cases occurred, and in 1897, with
21.02 inches, 8 cases of Filaria were recorded. Some other factor, therefore, is necessary for
the complete elucidation of this question, and, no doubt, temperature plays an important part,
the fluctuations in numbers being due to variations in temperature ; but the elucidation
of this part of the problem must stand over until more evidence is forthcoming.
With regard to the eight Australian horses, Nos. 43 and 45 to 51, there can be little
doubt where they acquired the Filaria ; for Spooner Hart, with an experience of over 30 years,
distinctly states that " he has never seen a waler landed in Calcutta with Filaria Oculi,
although thousands have passed through his hands." But he has known them to acquire the
affection within twelve months of their arrival in India. It is, therefore, logical to deduce
that not only the Australians but also the great majority of the country-breds contracted
Filaria Oculi during their detention at Karnal. A point of considerable interest is that,
since 1896, the ponds have been filled in and the animals are, more or less, stable-fed, now
that Karnal has been converted into a depôt for Australian horses. So that the ova must
gain an entrance into the digestive systems of the animals, from one of three sources, viz.,
from the lucerne grass grown under irrigation with water from the Western Jumna Canal
from the water obtained from wells, or from the hay collected in large quantities from the
estate, for it is unlikely that the parasite is carried in the corn, which undergoes clean-
ing and grinding before it is issued.
Saharanpur.
Saharanpur Depôt Estate.—One side of the Depôt estate for a distance of several miles
borders upon the Dâk road to Rajpur. The elevation of the surrounding plain is about
900 feet above sea level. The site is the best in the neighbourhood, but is neverthless low
and moist, for the water is near the surface, at a depth of seven to ten feet in March, and
close enough in the rains to reach it from above. All the surrounding land is, as a rule,
irrigated by means of canal water, as also some of the paddocks in the Government enclosure.
The estate more nearly resembles an English park than any other locality in India. It is
well timbered and intersected by lanes lined by hedges. The majority of the horses stocked
at Saharanpur are Australians; drafts arrive annually in Calcutta during the cold season of
the year, so that the numbers are always kept up. It will, however, be seen from the follow-
ing table that one-third of the included animals are country-breds.