212 
Theory and Practice of Dipping 
we have therefore added these values for the first five experiments 
(see Col. 6 et seq.). From these it will be seen that some 26 gms. of 
arsenious oxide are retained by the skin of a regularly dipped animal, of 
which 16 gms. are present in the hair and 10 gms. in the hide. From 
the figures it would appear that the quantity of arsenic remaining in 
the hide of a regularly dipped animal is much the same up to five days 
after dipping, but after a lapse of ten days the amount has been reduced 
by nearly one-half. From this it follows that between the fifth and the 
tenth day after dipping, some 3-5 gms. of arsenious acid have been 
removed from the skin, and as this removal most have been effected 
by the blood circulating in the cutaneous capillaries, the animal has 
received a continuous internal dose of arsenic at the rate of about 
070 gm. per diem, extending over five days. If, then, this amount 
of arsenic is absorbed by the blood from the fifth to the tenth day, 
what happens during the five days immediately following the dipping? 
We believe that the absorption of arsenic from the skin proceeds 
continuously from the time of dipping, but that for the first five days 
or so, the amount thus removed from the skin is constantly replaced by 
further quantities absorbed by the skin from the very considerable 
amount which dries on the surface. 
Appendix VII. 
The Augmentation of the Incubation Period of East Coast 
Fever by Dipping. 
In our own work, a direct practical test of the correctness of our 
deductions was carried out at Elliotdale (see Appendix VIII), but 
permission could not be obtained to carry on the work sufficiently to 
determine the details. 
Watkins-Pitchford, however, has since published his data of 
observations, showing that the incubation period of East Coast Fever 
is prolonged by dipping. He took three lots of five animals each, which 
were exposed on infected pastures for periods ranging from half an hour 
to nine hours. Lot A was undipped and served as a control to Lot B, 
dipped after exposure, and to Lot C, dipped before and after exposure. 
An abridged form of his schedule of results is given below. 
Lot Treatment Mean incubation period 
A Not dipped 9 days 
B Dipped directly after exposure 11 ,, 
C Dipped 24 hours before and immediately 17 ,, 
after exposure 
