THE AGRICULTUEAL NEWS. 



How Ticks are Killed i^-<j 



When Cattle 4^ ^h 



Are Dipped or Sprayed 



A knowledge of how a dip is absorbed by Ticks when catlle are dipped or spri^yeJ wllh an arsenical wash is of great assistance in elucidating die 

 problem of Tick destruction. Ahhough this subject has given rise to much conjecture, very little definite information is obtainable as a result of practical 

 experiment. Work directed by William Cooper and Nephews in South Africa has, hov.'ever, furnished results from which feasible deductions have been 

 made, and these appear to throw some light on the subject. 



The theories advanced by different workers are ; — 



1. That the Tick absorbs the poison through its own skin during the process of dipping or spraying. 



2. That the absorption of the poison through the skin of the Tick takes place after the operation of dipping or spraying is completed. 



3 Thit the poison is absorbed by the skin of the animal, and that the Tick sucks in the poison with the fluids extracted while feeding oi» 

 the animal. 



It follows from No. I theory, and it is asserted by those who favour this theory, that the longer the period of immersion of the animal in the tick-killing 

 Vai<J, the more certain is the destructive effect on the Ticks. For this reason the supporters of this theory advocate a dipping bath with a long swim. 



A; a result of the work carried out under the direction of William Cooper and Nephews, it has been established that a brief, thorough immersion of 

 the animal kills the Ticks as effectively as a long one. That is to say. complete immersion for a comparatively short time, ensured the death of the Ticks. 



If Ticks are taken off cattle soon alter they have been dipped or sprayed with an arsenical wash, and are tKoroughly cleaned to remove any externally 

 adherent arsenic, their bodies are found to contain no traces of the poison, whilst Ticks similarly removed on each of the six days following dipping are 

 found to contain appreciable quantities of arsenic, thus proving that the arsenic is absorbed after the operation of dipping or spraying is completed. 



With regard to theory No. 2, it is highly improbable that the arsenic is absorbed through the skin of the Tick, for the fluid dries on the skin in less 

 thm an hour after treatment, during which period, as was shown in the previous paragraph, no absorption takes place. 



There only remains then theory No. 3. vh., that the host animal absorbs the poison into its skin, and later, the Tick imbibes the poison during the 

 process of feeding. All experience with dips in the field goes to support this theory. 



Given dips v.iiich contain equal amounts of the poisonous agent, it has been proved by actual experiment that those which spread over and thoroughly 

 wet the whole s'jrface of the skin of the animal possess the greatest killing power. Therefore, an essential feature of a dip is that it should give complete 

 a.nd uniform penetration over the whole skin surface of the animal. 



It is a proven fact that those dips which saturate the skin in patches kill only the Ticks which adhere to those patches. It Is found, moreover, that If 

 a solution of arsenic is injected subcutaneously, the Ticks attached around the site of the injection are poisoned, and although they have had no contact 

 with arsenic from the exterior, their remains are found to contain appreciable quantities. This poisonous action iS limited to an .ii ea of about 6 inches radius 

 from the site of inoculation. 



Investigations have shown that arsenic applied to the undamaged skin of an animal does not appear In appreciable quantities in the Internal organs of 

 the body. This seems to prove that the arsenic which is absorbed by the skin fails to reach the circulating blood which would carry the poison from the 

 surface to the interior. The accumulated facts which have resulted from enquiries into the matter lend the greatest support to the theory that the living 

 cells, which form the deeper layers of the skin, have an actual affinity for arsenic, and the poison Is arrested and fixed in them and thus prevented from 

 reaching the circulating blood. If this theory Is correct, then after dipping or spraying, the deeper layers of the skin will become strongly impregnated 

 with arsenic, possibly in a stale of combination with the organic tissues. It Is then easy to suppose that while feeding on a beast which has been recently 

 dipped or sprayed, the tick takes in considerable quantities of the poison with the blood and lymph which have necessarily passed through these deeper 

 layers of the skin, which are more or less saturated with arsenic. _ 



COOPER'S CATTLE TICK DIP WEST INDIAN AGENTS : 



,, . J.. cc- ■ I I r ,L r II .■ /- . • ST. KITTS : 5. I.. Hor.sford &Co. ANTIOl'A : Bennett. Bryson & Co. 



Has recewed the off.cal approval of the followng Countries: *■• Ml i. -j-^^^,^.^. ^ „^„d„,„„ & Co.. KinK-..ton. 



Union of South .Africa, Northern Rhodesia, Brazil, Basutoland, OR[:NaDA: Tliomson. Ilankey & Co. 



_ , „, . , ... BARBADOS: Barbados Co-opir.iti\ c Cotton Co.. Ltd. 



Nyasaland, Swaziland, Southern Rhodesia, Madagascar, TRiNinAi): T. Otddcs Uruni. Port of Spnin. 



British East Africa, (icrman East Africa, Portuguese East Africa, *" BRn l.sit UL'lAlNA: .«andh.ich. l>urker & Co. 



,,,,.,, c t A .1 Do...kii.. n„.>.„.i..j ST. VINCENT: Coroa & Co.. Klnirstown. NbViS: S. D. Malone. 



Portuguese West Africa, Egypt, Argentine Republic, Queensland, DANISH wnsT INDIhS: Carl v. I.a Beet, St. Tliomas. 



^United States of America, Northern Territory of Australia. montsi^rrai: \v. i.icwcilvnWali. do.mimca: Hon. ll. a. Frampton 



Manufacturers : WILLIAM COOPER & NEPHEWS, Berkhamsted, England. 



BRANCHES : ToroDto, Chicago, Sydney, Mtlboorne, Aucklanil, Buenot Aires, MoDte Video, Puct« Arenas, East London, Odcua. 



