THE 



AGRICULTURAL JOURNAL. 



221 



been to find a dip which will kill ticks 

 and not injure cattle. In America suc- 

 cess is reported to result from the use of 

 "extradynamo" oil saturated with sulphur, 

 and used so as to entirely fill the dip, no 

 water being added. 



So far as I am aware, no systematic ex- 

 periments on di])])ing have" been con- 

 ducted in Australia. Though it would 

 probably he expensive, such work is much 

 needed ; for since inoculation affords pro- 

 tection against tick-fever, the weakest 

 point comes to be our defencelessness 

 against the parasitism of the ticks. At 

 the present time the most pressing de- 

 sideratum of the tick question is the dis- 

 covery of a means of destroying ticks 

 which will at the same time be innocuous 

 to cattle. 



Eemote Effects of Inoculation. 



As the inoculation illness and its im- 

 mediate effects have been deseri1)ed in my 

 previous report, it is only ni'Ci'-sary here 

 to briefly refer to the suhsciiurnt health 

 of the cattle. The animals retained 

 under observation at Xorth Head after in- 

 oculation all remained perfectly well dur- 

 ing the period of sixteen months covered 

 by the experiment. Neither the relajxes 

 nor chronic ill heilth de^crihcd as seque- 

 lae of natural tick-fever ap])e:ireil in any 

 of them. The three animals uuder my im- 

 mediate supervision were all dairy cows. 

 They were milked regularly when in milk, 

 fed mainly on lucerne, and in other re- 

 spects treated in the ordinary way. From 

 being originally poor and thin, they be- 

 came fat, sleek, well-looking beasts, and 

 two of them gave birth to healthy, well- 

 nourished calves. The animals sent to 

 the North Coast districts have had a much 

 less peaceful time, and have been travel- 

 ling at intervals. I am informed they 

 have not done so well, but have remained 

 free from sickness of any kind which 

 could be regarded as the result of their 

 inoculation. Two of them have calved. 



Our observations go to show that in- 

 oculation is not necessarily followed by 

 any deterioration of the genernl healtli, 

 and that after recovery from the opera- 

 tion the animals differ from nninoculated 

 animals neither in appearance nor vigour. 

 The profound change which has resulted 

 from the inoculation only becomes re- 



vealed when the animals are reinoculated 

 or exposed to ticks, or when their blood is 

 used to inoculate other animals. 



Inoculated Animals kesist second 



ATTACKS. 



I have never personally observed a sec- 

 ond reaction in inoculated animals, al- 

 though 1 have reinoculated different ani- 

 mals at intervals of six, eight, ten, and 

 twelve months after the first (reacting) in- 

 oculation, and the blood used always pro- 

 duces reaction in controls. The protec- 

 tion against reinoculation has remained 

 perfect in every such case coming under 

 my direct notice. It has been reported 

 to me that second reactions were observed 

 in the course of the inoculations carried 

 out in the North Coast districts. They 

 only occur occasionally, and always to 

 young animals. The conditions under 

 which the inoculations in question were 

 performed precluded detailed investiga- 

 tion of the causes underlying this unusual 

 feature of inoculation. 



Fourteen of the North Coast animals 

 were all treated with the same bloods, at 

 the same time, &c., but on exposure to 

 the ticks exhibited great variation in re- 

 sistance to tick-fever. No. 48 escaped at- 

 tack ; No. 25 had a slight attack ; Nos. 

 15, 10, -3:, 4:], 55. 57, and (52 had mode- 

 rate attaeks ; Nos. ID, 22, 51, 5-1, and Gl 

 had ]iii;li fever ; whilst No. 22 died. It 

 will Ijo seen, then, on the one hand, that 

 in certain animals the resistance was 

 equally perfect although the inoculation 

 treatment had been different in each case, 

 and on the other hand, that in certain 

 other animals the resistance exhibited 

 was very different, although the inocula- 

 tion treatment was the same in each case. 

 Further examination of the data failed 

 to reveal corres|>()n(lence between any 

 special feature of inoculation and the 

 amount of resistance obtained. The issue 

 ap]:>('ared to depend more on the indi- 

 vidual peculiarities of the animals than 

 upon anything under human control. 



The observations indicate that inocula- 

 tion may be indulged in without fear of 

 permanently injurious consequences, pro- 

 vided, of course, that it be carried out in- 

 tellio-ontly and with a reasonable amount 

 of care. They also tend to show that the 



