HORSE-SICKNESS 839 



The blood and the pulmonary and conjunctival exudates are infective. 

 No micro-organisms have been demonstrated in these fluids neither have 

 organisms been cultivated from them. 



The filtrate obtained by filtering the undiluted exudate or blood mixed 

 with serum through a Berkefeld or Chamberland F bougie will reproduce 

 the disease on inoculation into a susceptible animal (McFadyean). The virus 

 will pass through a Chamberland B bougie provided that the exudate has been 

 diluted with 30 volumes of water. 



In places where horse-sickness is prevalent a very similar disease is observed in 

 sheep, goats and cows. This latter disease is known as catarrhal fever of sheep (blue 

 tongue, mouth sickness, heart- water, catarrhal malarial fever, etc.) : it appears to 

 be different from horse- sickness, and is also caused by a " filter passer." The 

 filtrate obtained by filtering the blood or serum (Berkefeld bougie) is infective 

 (Theiler and Robertson). 



SECTION IV. THE VIRUS OF RINDERPEST. 



(Cattle plague.) 



Rinderpest is essentially a disease of bovine animals, but it also affects 

 some races of sheep, goats and pigs. The blood, exudates and juices from 

 the internal organs are infective, but the causal micro-organism can neither 

 be seen nor cultivated. The virus easily passes through a Berkefeld bougie 

 and, under certain conditions and with difficulty, through a Chamberland 

 F bougie. 



SECTION V. THE VIRUS OF BIRD PLAGUE. 



Bird plague must be carefully distinguished from fowl-cholera (Centanni 

 and Savonuzzi). The disease, which is fairly widely distributed, may affect 

 all farm-yard birds and especially pheasants ; it is due to an invisible organism 

 (Maggiora and Valenti). The pleural, pericardial and peritoneal exudates and 

 the blood of diseased birds are infective. The virus will pass through a 

 Berkefeld or Chamberland F bougie and even through Chamberland B. 



Marchoux has succeeded in growing the virus of bird plague : after ten 

 successive sub-cultures, a dose of 0*20 c.c. of the blood in which the virus 

 was sown killed fowls in 2 days. The cultures are grown at 37 C. in 

 defibrinated fowl blood spread on a thick layer of glucose-peptone-agar : 

 growth does not take place through the whole of the blood but only in a 

 .zone near the surface of the agar. 



SECTION VI. THE VIRUS OF SHEEP-POX. 



Synonym. Variola ovina ; Fr. La Clavelee. 



The virus is present in the pustules and in all the lesions of sheep-pox. 

 No organism has been discovered. The virus cannot be cultivated and 

 does not remain in the blood. 



The juice obtained by scraping the pustules when diluted with water and 

 filtered through a Berkefeld bougie will yield an infective filtrate. The virus 

 will not pass through a Chamberland F bougie if the material be filtered 

 rapidly and at once, but if the filtration be carried on continuously for from 

 1-7 days the virus will then appear in the filtrate (Borrel). 



When the virus is diluted with non-sterilized tap water a number of very small 

 vibrios and spirilla pass through the bougie with the virus of sheep-pox : these 

 water organisms (which can be stained by Lceffler's method, p. 149) multiply in 



