W. F. Cooper and H. E. Laws 
203 
The Effect on Pathogenic Organisms of Arsenic in the Blood 
of Biffed Animals. 
It has been shown that the epidermal cells possess a special affinity 
for arsenic (see pp. 200-202 and Appendix VI), and once this arsenophile 
proclivity is satisfied, the excess of arsenic is available for absorption 
by the blood. 
It is obvious that the total amount of arsenic in the general blood 
system cannot be very great, since the general health of the animal is 
not interfered with in any way. But a consideration of the amount 
of arsenic applied every week, or even at shorter intervals, and especially 
the appearance exhibited by the inner surface of the skin of an animal 
which has been dipped in a solution only slightly too strong, would 
lead us to suppose that the amount of arsenic present in the blood 
circulating in the most ferifheral vessels of the skin would be very 
considerable. It is quite conceivable that the blood circulating in 
the capillaries which are in close relation to the external surface of the 
skin to which the very strong dose of arsenic has been applied, might 
contain a very large amount, far greater in fact, than the amount that 
would be possible in the general blood system; for this peripheral 
blood containing a large quantity of arsenic would be immediately 
diluted by the general mass of the blood from the internal parts of the 
animal, so that the total amount in general circulation would not be 
excessive. 
This is what we consider actually takes place, and the results attained 
at Elliotdale (see Appendix VIII) are sufficiently good evidence that 
this deduction is correct; and upon this deduction we base our antici¬ 
pation of success in our experiments at present in hand. 
In the case of such diseases as are transmitted by external parasites— 
East Coast Fever for example—the infective organisms can only be 
injected into the most peripheral cutaneous capillaries, where the 
concentration of arsenic is sufficiently great to kill them. Such being 
the case, regularly dipped animals running on infected pastures would 
remain free from the disease. 
Watkins-Pitchford (1911a, p. 56) has given figures to show that the 
incubation period of East Coast Fever is prolonged in dipped animals; 
we give an abstract of these in Appendix VII. In connection with these 
results, it should be observed that the cattle were only dipped a few 
times before exposure to infection and that after exposure they were 
not dipped at all. 
