316 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [ I, IV

blue ticks and which died as a result of this infestation, from acute anæmia, owing
to the withdrawal of blood. Within three days 14 lbs. weight of blue ticks were
collected which had dropped off this horse, and this amount only represented about
half of the ticks which engorged themselves on it ".

According to Hutyra and Marek, " The chief effects of the ticks as ectopara-
sites are exerted as blood suckers. Their number increases to many thousands,
each one gorging itself with blood day after day (a female Ixodes recines takes 0. 4.
c. c. of blood). As a result of the destruction of red blood cells (some 7 to 10 per
cent. of the total amount) follows the history of the ticks, while at the same time
a poisonous saliva is excreted by them. After absorption of the toxins the symp-
toms of generalised affection, uneasiness and emaciation ( " Tick worry " ) appear,
which grow worse in hot weather".

From the above two quotations it would appear that the chief injurious effects
of the ticks as ectoparasites are believed to be caused by the abstraction of blood
by the ticks. A mere abstraction of blood can hardly be regarded as a factor of
any importance in accounting for the disease. The writer has noted that larvæ
of intermittent feeders, which do not suck appreciable amounts of blood can also
produce the disease, and the observation finds confirmation in the statement made
by Hutyra and Marek [ 926], namely, guinea-pigs that are bitten by larval ticks
die within three days. Again, Marrillat [1916] states, " it is well known that the
abstraction of a limited amount of blood or even a large amount has no harmful
effects upon a healthy animal. Instead it improves the general health by exciting
vital forces to renewed activity to réplenish the loss". Smith [1912] says " Perci-
vall tells us that in the horse he occasionally drew 3 gallons of blood, which may
be taken as half the amount in the body, apparently without fatal consequences "
and he further states, " Regeneration of the fluid portion of the blood is extremely
rapid, experiments showing that after slight hæmorrhage the normal volume is
regained within a few hours. This is supported by clinical observation; in the days
of severe bleedings venesection to the extent of producing syncope was frequent,
yet in a short time the volume was restored ". The following familiar fact is one
more example to the point. The so-called rinderpest serum producers are bled at
the progressive rates of 4 c. c. and then 6 c. c, 7 c. c. and 8 c. c. per pound body
weight 15 times at intervals of three days and are subsequently utilised for the pro-
duction of other sera or are sold. The amount of blood drawn out from the body of
a serum producer, whose weight is 600 lbs., in these 15 bleedings amounts to 115 lbs.
or 19 per cent. of the body weight during a period of 43 days. Nevertheless, the
animal does not succumb to such heavy bleedings except for rare cases of death by
shock. From the extensive observations made by him, the writer has found that