564 



SPOEADIC DISEASES. 



elusion arrived at was that the organism was communicated by 

 the tick from louping-ill districts to the sheep, for the same 

 organism was found to be developed, but not quite so quickly, 

 in the cultivation as in that containing the tick from sheep 

 suffering from louping-ill. 



Fig. 34. 

 Cultivations from Blood of Tick. 



(Drawing by Dr. Jas. Hunter, 18S2.) 



a. Single rows of bacterioid segments with traces of a double row remaining. 



h. A few rods seemingly imperfect. 



c. Zooglcea. d. A perfect and entire rod. e. Mycelium. 



This last experiment, repeated over and over again, proved 

 the fact that the ticks experimented with contained the 

 spores of the organism, and were capable of infecting sheep ; 

 and that the reason that all sheep were not infected was 

 simply the fact that many sheep were able to resist the inva- 

 sion of the organism, or suffered so slightly that they were not 

 observed to be ilL 



Many sheep even badly affected recover from louping-ill, and 

 it is fair to conclude that the organism has but a transient effect 

 upon many others ; that in fact, as is the case with other 

 diseases, many are able to throw it off, and are most probably 

 by this inoculation rendered proof in many or even the majority 

 of instances against any further infection. This conclusion is 



