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

tioned, all the treated animals were found free from infection. Concurrently,
280 camels from the adjoining areas were also examined, and of these 79 were
found affected. From these observations, the authors conclude that under
natural conditions Naganol protects for at least 3 months.

The findings of Yakimoff and his collaborators, as reproduced above,
strikingly illustrate the extent to which the natural conditions of a locality
contribute towards the success of any operations designed to combat natural surra
of animals by means of Naganol prophylaxis.

A mention should be made here of a very recent paper by Bubberman
[ 1931 ], where reference is made to certain experimental observations indicating
that in the horse a prophylactic dose of 1 gramme of Nagonol per 150 kg. body
weight will produce in the majority of cases " a condition of non-susceptibility "
to natural surra which will last for a month or more.

A brief reference may also be made to the experiments carried out by Berg
[ 1925 ] upon the prophylactic action of " Bayer 205 " against cattle trypanoso-
miasis in South Africa. As one would expect from what has been said earlier in
regard to the action of this drug on T. congolense infection, the results obtained by
Berg were very disappointing, the drug having conferred practically no protection,
even when employed in doses of 10-25 grammes, for cattle exposed to natural
infection in fly belts 2 days after the inoculation.

From the records summarized above, it would appear that except for the
congolense group of trypanosomes, " Bayer 205 " has been more or less successfully
used for prophylactic inoculation against all of the common species of trypanosomes
affecting domesticated animals. The failure of the drug to affect trypanosomes of
certain species, while it is endowed with marked trypanocidal properties for others, is
a point of importance for workers in India, inasmuch as this might be held to explain
any failure on their part to use the drug successfully against individual cases of
animal trypanosomiasis, which, although apparently due to T. evansi, might, in
reality, be due to some other undetermined species of "small" trypanosomes
analogous to one of the species of the congolense group of trypanosomes. It would
be useful to remember this possibility in dealing with outbreaks or sporadic cases
of " surra " in India, and to endeavour definitely to establish the identity of the
causative parasite whenever cases are encountered which appear markedly
resistant to the prophylactic or therapeutic action of " Bayer 205 ".

    RECOMMENDATIONS, WITH A DISCUSSION ON THE GENERAL PRINCIPLES OF

          PROPHYLAXIS AGAINST EQUINE SURRA BY MEANS OF " BAYER 205 ".

A perusal of the available literature shows that few workers have made actual
recommendations in regard to the employment of "Bayer 205 " for prophylactic