W. F. Cooper and H. E. Laws 
207 
effects on the skin of both arsenic and paraffin. With the same view 
the authors tried glycerine but, as it seemed to have little effect, and 
the cost prohibited its use on an extensive scale, they dropped it. It 
will be observed that Watkins-Pitchford omits glycerine in his final 
formula (1911a, p. 37). 
Appendix III. 
The Effect on Ticks of Arsenic administered •per os. 
The object of this experiment was to ascertain whether it was possible 
to destroy attached ticks by dosing the host with arsenic. By internal 
dosing, it was surmised that some of the arsenic would be taken up by 
the blood and thus conveyed to the skin. The lethal dose of arsenic 
for cattle is stated by Ivaufmann (see footnote on p. 202) to be 4-8 
drachms (= 15-5-31 gms.). 
Beast No. 
1200. d, 
aged 2J years. 
Date 
1909 
Temperature °F. 
Effect on ticks 
Remarks 
March 9th 
0-75 gm. (lip grains) of As 2 0 3 
administered per os 
„ 10th 
104-0 
None killed 
„ 11th 
103-0 
„ 12th 
105-7 
9 9 
Diarrhoea 
„ 13th 
104-2 
99 
„ 14th 
103-4 
99 
„ 15th 
105-8 
99 
„ 16th 
106-6 
99 
Up to March 16th, no ticks were killed. The animal was not showing 
any signs of arsenical poisoning. This beast had been continuously 
dipped prior to tbe commencement of this experiment and as it had not 
shown any untoward symptoms after the initial dose of 0-75 gm. we 
assumed that it had acquired some degree of tolerance, and it was then 
decided to reduce the dose and administer it at frequent intervals: 
Date 
1909 
Temperature "F. 
Effect on ticks 
Remarks 
March 31st 
103-2 
None killed 
0-3 gm (5 grains) of As 2 0 3 
April 1st 
104-4 
administered 
99 it 
„ 2nd 
104-2 
99 9> 
,, 3rd 
103-4 
99 99 
„ 4th 
104-6 
,, 
9i >■ 
„ 5th 
103-8 
Beast emaciated 
„ Cth 
102-8 
,, 
Beast breathing hard, bowels 
„ 7th 
99 
very loose 
Beast found dead 
