THE rR()l!LI':M Ol-- IIOKSK SICKNESS. 75 



(2) Animals that Slunccd a Dtinkop Reaction to tlic Orif/ina! 



Injection. 



Immune to _ Tzaneen 



Ordinary Virus 



per cent. per cent. 



Now failed to react to any tests • • . . 71 18 



Sliowed one (a second) or more Dunkop reactions and | ) 



recovered - • ■ • • • • • 4 - 4 19 1- 30 



Showed one or more Dikkop reactions and recovered Nil) llj 



Showed one or more reactions and finallv died of Dunkop J5 I ^_ 45 1 -, 



Dikkop Nil J -^^ 7i ^^ 



Abstract. 



Total survi\'ors from tests . . • • • • 75 46 



Dunkop form produced bv tests in • • ■ ■ 29 66 



Dikkop ,, ,, ,, •• ..Nil IS 



(3) Animals that shozced a Dikkop Reaction to the Original 



Injection. 



Immune to Tzaneen 



Ordinary- \'irus 



per cent. per cent. 



Now failed to react to any tests • • • • 77 _'l 



Showed one or more Dunkop reactions and recovered Nil | 4J j 



Showed one (a second) or more Dikkop reactions and [• 6 - 54 



recovered .. .. .. .. 6J llj 



Showed one or more reactions and finallv died of Dunkop 15 i.„ IS I ^. 



Dikkop 2 } 11 1"-^ 



Abstract. 



Total survivors from tests 

 Dunkop form produced by tests in 

 Dikkop 



(4) Total Number of Animals that Reacted (both forms) to the 



Original Injection. 



Immune to Tzaneen 

 Ordinary Virus 



per cent. per cent. 

 Now failed to react to any tests . . . . 74 19 



Showed one or more reactions (either form) and rectnered 5 42 



died 21 39 



In considering these results, it will be noted : 



I. That there is still a certain percentage of horses that 

 completely fail to react to all injections. (By failing to react, I 

 mean that no febrile reaction occurs, and the horse does not 

 show any clinical symptoms of horse-sickness.) In the case of 

 ordinary virus, this percentage is 20 per cent. — that is to say, 4 

 per cent, of the original nuniber of horses completely resisted 



