E. L. TAYLOR AND K. M.
SANDERSON
161
partcuilarly well, Haemonchus appears to be less sensitive and Trichostrongylus
and Cooperia occupy an intermediate position in this respect.
One interesting point which came to our notice was the very good action
of the drug on Trichostrongylus axei in the fourth stomach of sheep—100 per
cent frequently being removed—and its comparative lack of action on the
same species when present in the stomach of the horse.
The action of the drug on worms in the small intestine of sheep is less
pronounced than on those in the fourth stomach but is, nevertheless, better
than that of any previously known anthelmintic. Apart from Moniezia, on
which there is no action, Nematodirus appears to be the most resistant, but
other species of trichostrongylid parasites in the small intestine may be regard-
ed as giving a satisfactory response.
The results clearly show that there is no action upon Fasciola, nor upon
Anoplocephala.
Action on ascarids is interesting in that it appears to be very good in the
horse, moderately good in the pig and almost completely lacking in the dog,
as shown by Montgomerie's results. This comparative response of ascarids to
phenothiazine in these three kinds of hosts differs from their response to carbon
tetrachloride as reported by Hall who found this drug to be more efficient
against Toxocara and Toxascaris in the dog than against Ascaris in the horse.
ANTHELMINTIC EFFECT ON THE HOST.
The beneficial effect of treatment with phenothiazine has been very clearly
demonstrated in some of the weighing experiments in which great gains have
been observed as a result of the anthelmintic action of the drug. The most
striking is described in Experiment 3 in which one 20 gramme dose to each of a
group of lambs resulted in the production of 336 lb. of mutton.
Observations carried out by McEwen and Taylor (to be reported later)
and by McEwen alone on the Romney Marshes show significant gains in pheno-
thiazine-treated sheep, over and above gains made by similar sheep treated
with a mixture of nicotine sulphate and copper sulphate. A difference of 9 lb.
per head among a group of 27 lambs was noted in one instance.
The results obtained by J. W. Ironside and K. D. Downham (reported in
this paper) in lightly infected flocks are also interesting, showing a slight gain
in favour of the treated groups. The trials were, however, not sufficiently
extensive to establish this point and the result obtained by S. J. Menzies (also
reported here) in comparing phenothiazine with copper sulphate suggests that
the effect of copper sulphate may be equally good in instances of slight infesta-
tion. On account of the inadequacy of data, however, this point cannot be
regarded as certain.
Very good results have been observed wherever it has been tried in horses.
The effect in goats and in cattle has also been very good, apart from the
toxic action that has been observed in some instances.
TOLERANCE AND TOXIC ACTION.
Domestic animals in general appear to be extraordinarily tolerant to this
drug and there is usually found to be an enormous difference between the
anthelmintic dose and the toxic dose. Two sheep and one goat were actually