THE AGRICULTURAL NEWS. 



How Ticks are Killed 9- 



When Cattle 

 Are Dipped or Sprayed 



A knowle<)ge of how a dip is absorbed by Ticks when cattle are dipped or spr&yed with an arsenical wash i« of great assistance in elucidstin^ the 

 problem of Tick destruction. Although this subject has given rise lo much conjeclure. very little definite information is obtainable as a result of ^Tactical 

 experiment. Work directed by William Cooper and Nephews in South Africa has, however, furnished results from which feasible deductions haie 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 ihe 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 That the poison is absorbed by the skin of the animal, and that the Tick sucks in the poiion with the fluids extracted while feeding on 

 the animal. 



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

 fluid, 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. 



As 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 after they have been dipped or sprayed with an arsenical wash, and are thoroughly 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 lo 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. 

 than 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, viz., (hat the host animal absorbs the poitOD mto its skin, and later the Tick imbiba the poison during lh>e 

 process of feeding. All experience with dips in the Geld goes to snpport this theory. 



Given dips which contain equal amounts of the poisonous agent. It has been proved by actaal experiment that those which spread over and thoroughly 

 wet the whole surface of the skin of the animal possess the greatest killing power. Therefore, an essmtial feature of a dip is that It should give complete 

 and uniform penetration over the whole skin luiface of the nnimnl 



It is a proven fact that those dips which saturate the skin in patches kiQ only the Ticks which adhere to thoae patches. It ii fonnd. moreover, that if 

 a aoluiion of arsenic is injected subcutaneously, the Ticks attached aroond the lite of the injection are poinoed, and although diey have had no contact 

 with arsenic from the exterior, their remains are foond to contain appreciable qiuntitie* Thii polsonoiu adiaa i< limited to an area of abont 6 inches radiu 



the site of inoculation. 



Investigations have shown that arsenic applied to the endamaged ikin of an aniaal doc* not appear in appreciable quantities in the internal orf^tu ol 

 Ac body. This ^eems to prove that the arsenic which is absorbed by the skin fails to reach the drcalating blood which woold carry the poison from ilw 

 tarface to the interior. The accumulated facts which have resulted from enquiries into the matter lend the greatest support lo the theory that ihr Lting 

 •ells, vliich form the deeper layers of the skin, have an actual affinity for arsenic, and the poisoo is arrested and fixed in them and thus prevented lrt>m 

 fetching the circulating blood. If this theory is correct, then after dipping or spraying, the deeper layers of the akin will become strongly impregiiAied 

 with arsenic, possibly in a state of combination with the organic tisioet. It is then easy to suppose that whSa feeding on a beast which has been receaijy 

 dpped or sprayed, the lick lakes in considerable quantities of the poisoo with the blood and lymph which have neceuarily passed tfaroogh these ( 

 Wan of the skin, which are inore or lest saturated with ars< 



COOPF-RS CATTLE TICK DIP WEST JNPIAN AGENTS : 



,-. , , ,r ■ I , r .1. r II ■ f . ••.. ANTKil'At I5i-nnclt. Krvs.iii & Co.. .<t. Johllii. 



Hat rrce.vrd Ihe official approval of the foU owing Counlriea. BAIIAMA.I: H. T. Uricf. Na.<.«au, N.P. 



BAKBAtXt-'i: B;irlindo.> Co-optratiM; Cotton Co.. BrldltetowB. 

 Tnic-ii o( iioul.h Afrif;!. Norltiepn RhoifL'.ift, Brazil. Basuto'and. Bf^ll IStI (it lANA : T. tieitdt-s tirant. l-td. 



Nva«U..ci. Swazil.nd. South.rn Rhodesia. Mada^aNtar. DJ.MINIC A: ll.m. tl A. I riimnCon. (ikl;^ U)A ; Tliom.son. Honkrv A C«. 



(•l.AI>tlt.<>l 'IM. ; I ht- .station Aurnniimlque dc la Guadeloupe, 

 ftnliah E«M AM'ii. t'rntian P*it Alrica Portui^ucst East Africa. I'oint-.i-rilri;. .lAMAICA: I). Meiidcr.'son & Co., Kinaataa. 



F.,r..«.,e,.K;..Alr.a. L«,.„t. Ar,enU„e B.„.,„l. . Queensland. „ONr>" k'^V^"^V 'Yi:;Jf^^ W^t.^-'^^^T^tT' M...0. 



I o:t<:d S:at«> of America. New Soul ti Walev aT. Mil."- >. I.. Ilorslnrd & Co. 5T. i.l'CIA: Barnard .Aon? 4 (i«., 



C.>.<lrie*. ST. VINCKN I : Cores & Co., KInotown. 

 N<.flhfr.i Tfrnl<;r\ i-f Australia. TMINIDAI) A: TOBAUO: T. Oeddes Grant. Ltd. 



AMEk'KAN Nll^dlN I.SI.ANOS: (>. H. Sctimiecelow. St. Oreil. 



Manufacturers : WILLIAM COOPER & NEPHEWS, Berkhamsted, England. 



tK<.h(HI.S ; Toiorlo, (.l.ir»)< ^.dnt\. Mrlliuurni , AiirlalaDd, [liieBi.i . iii-i Tt'onli \U'ta. Fynll Armas, Johaanctbure, OlIeMa. 



