W. F. Cooper and H. E. Laws 
215 
quantity, and the presence of the precipitate does not inhibit the action 
of the dip in any way. 
It has been shown (pp. 197-198) that the presence of an emulsion in 
the dip facilitates wetting, the importance of which latter factor is demon¬ 
strated in Appendix V. Both Watkins-Pitchford and Briinnich and 
Smith have called attention to the ease with which certain parts of the 
body (as under the tail) escape wetting. Hence it is a matter of vital 
importance that the solution should have the maximum possible wetting 
power, and any addition which increases this factor is more than 
justified. 
A point which is generally disregarded in matters concerning the 
theory of dipping is the cumulative effect (pp. 200-202). For instance, 
Theiler (1911, p. 505), writing on the subject of the eradication of 
East Coast Fever, states: ‘When the disease has taken a firm hold on 
a farm, that is to say, a number of cattle sickened and died and dis¬ 
seminated ticks in large numbers, then no dipping will help to stop the 
disease.’ Further, on p. 508, he warns farmers ‘not to trust to it 
(dipping) as a panacea for the prevention or eradication of East Coast 
Fever... .No dip has yet been found which prevents ticks from biting, 
and as long as infected ticks are present, so long East Coast Fever will 
be found.’ 
We claim that on account of the cumulative effect the fact that 
the ticks bite does not matter. Watkins-Pitchford (1911a) showed most 
conclusively that the ‘Laboratory dip’ kept stock clean after a few 
dippings at five-day intervals. On p. 18 he says: ‘Such ticks as have 
attached themselves to the cattle have been regularly destroyed.’ In 
Schedule “B” (p. 54) he shows that ticks placed on a recently-dipped 
beast may attach, but, if they do, they are killed within a period of 2-3 
days after dipping. Schedule No. 21 (p. 38) shows that after ten dippings, 
the animals remain free from ticks, provided the dipping is repeated at 
five-day intervals. 
On the basis of these observations of Watkins-Pitchford we are at 
a loss to see how such statements as those cited from Theiler’s paper 
can be reconciled with actual experimental data. 
Further, these remarks have been shown to be invalid in actual 
practice, in a paper published by Manning and During (1912). They 
give details of a case (p. 451) in which East Coast Fever broke out in a 
herd of 805 cattle in April, 1911. By the end of September, up to which 
time very desultory dipping had been practised, 221 head had died of 
the disease. Five-day dipping was then established and in the following 
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