298 A TICK-RESISTANT CONDITION IN CATTLE. 



It should be of interost to (»)).serve tho result of mating 

 resistant cows with a resistant bull. By so doing one 

 should be able to readily decide what part heredit}^ pla-ys- 

 Moreover, if the quality be jirovetl to be inheritable from 

 either parent, no matter whether as a dominant or a recessive, 

 then a ready means of increasing the number of resistant 

 cattle in a herd is available. 



2. Transiiiission by " vaccination " : — There is a con- 

 siderable amount of evidence in favour of the view that 

 resistance can be transmitted by '" vaccination," i.e., by 

 taking a little of the exudate from a resistant animal and 

 rubbing it into an abrasion on a ticky subject. Mr. Hull 

 experimented on this line with some success, but since at 

 first he waited for a scratch or horn wound to appear on the 

 ticky animal at the same time as fresh exudate was available, 

 his progress was necessarily slow. Later he performed the 

 scratcliing with a clean knife. During the last few years 

 he has given up vaccination since he considers the animals 

 become tick free naturally if left alone. The results of 

 A'aecination of the following ten animals were :— 



Jessamine . . 

 Laidybiixl 

 Woodbine . . 

 Fair\- 

 Mandy 



Prettyface . . 

 Brownie 

 HoUy 

 Zephyr 



JCiglit out of ten thus Ijccame resistant, usualty in the 

 following year and in one case in tlie second 3'ear after 

 vaccination. As a contrast of this apparent success one 

 maj' consider the case of the 10 heifers purchased from 

 Rosewood in 1911 ; these \\ere never dipped nor (with one 

 exception, Beauty) were they vaccinated, yet eight out of 

 nine survivors became tick resistant in periods ^-arying from 

 t"HO to four years : the four Avhich have been retained are 

 some of the most strongly resistant animals on the place. 



Positive evidence of the efficacy of vaccination was 

 given by Mr. Henderson (R.S.C. 1915, p. 41). Of nine 



