214 
Theory and Practice of Dipping 
At the end of June, the experiment was left in the charge of our 
agent until it could be taken over by a stock inspector at the end of July. 
In April, 1911, eleven months after the commencement of the 
experiment, Mr A. H. Stanford, the Chief Magistrate, reported that all 
the stock in the district had succumbed, except those which had been 
sprayed. Among the latter, with the exception of the two cases men¬ 
tioned above, not a single death occurred and the herd had increased 
to some 600 head. 
The experiment was continued for a further six months, by which 
time the results were becoming generally known among the natives 
throughout this part of the Transkei. Consequently they introduced 
other stock, at first surreptitiously, many of which were heavily 
infested with ticks. It was impossible, owing to the absence of fences 
of any kind, to prevent the promiscuous mixing of these newly-intro¬ 
duced animals with the domiciled stock, and eventually such large 
numbers were brought into the area that it became impossible to deal 
with them and the work had to be abandoned. 
This experiment cannot be regarded as a strictly scientific investi¬ 
gation, but it proves in a very conclusive manner that dipped cattle 
remain immune for indefinite periods although they are allowed to run 
on heavily infected pastures and to mix freely with undipped stock 
which were dying from East Coast Fever. 
As a matter of fact, in such a case as this, where the ‘controls’ were 
so numerous, there was no necessity to make a definite proof that the 
deaths in the undipped stock were due to a Theileria parva infection. 
The disease had been diagnosed at its outbreak as East Coast Fever 
by a competent authority, and the subsequent deaths were clearly 
attributable to the same cause. 
Appendix IX. 
In most of the published work on the effects of dipping very little 
consideration has been given to the essential importance of the addition 
of an emulsion. The objection generally raised, e.g. Dixon (1911, p. 16), 
is that when hard or brackish water is used in the preparation of the 
dip, the soap used in the preparation of the emulsion is precipitated 
and rendered useless. 
We claim that, by this precipitation, calcium and magnesium salts, 
which otherwise would form ineffective arsenates, are removed. The 
amount of soap thus rendered inert is at the most relatively small in 
