THE ALIMENTARY CANAL AS A SOURCE OF CONTAGION ^ 



Some of them, such as Braxy, appear to be pecuHar to the sheep, 

 while others, such as Blackquarter, are common to it and to cattle. 

 Louping-ill, although pre-eminently a disease of the sheep, is said to 

 affect other animals, such as the calf, the pig, and the goose, but only 

 on rare occasions. 



Each of the diseases in question is caused by an anaerobic bacillus 

 having a great tendency to spore, and whose natural habitat is the 

 intestine. Doubtless they can all be inoculated upon the skin, and, 

 when thus transferred, occasion a " Blackquarter " slough, but it is a 

 mistake to suppose that even in the case of so-called " Blackquarter " 

 this is the usual method of invasion. The " Blackquarter " slough is 

 simply the manifestation of the effects of the action of the virus when 

 implanted superficially upon a scratch or puncture wound, and can be 

 called forth by any of them, while the commonest method of intro- 

 duction, and this holds good of the whole class, is through the stomach 

 and intestine. 



Whether Malignant CEdema of the sheep is the same disease as 

 that which affects other animals and man, and which goes by the same 

 name, I am as yet unable to say, but quite possibly, from its occurring 

 so frequently in the sheep, it is altogether a different malady. 



There is another disease of the same class which is peculiar to 

 the deer, but which as yet does not seem to have been identified or 

 described. 



Their Periodicity. — One remarkable feature of these diseases of the 

 sheep and the deer is that they occur periodically, that is to say, at 

 stated times of the year. Certain of them, such as Braxy, Disease 

 " A," Disease " B," and Malignant CEdema prevail in the autumn and 

 winter months, while others, and more particularly Louping-ill, are 

 diseases of the spring ; all of them tend to vanish during the summer. 

 They show themselves, almost to a day, each in its season, and vanish 

 quite as regularly and mysteriously. 



Areas Affected. — They prevail only in certain districts, and mainly 

 along the west coast and southern counties of Scotland and the northern 

 counties of England, while the east coast of the whole of Great Britain 

 may be said to be almost exempt from their ravages. Draw a 

 straight line from the north of Scotland down to the south of England, 

 and you practically separate the infected districts from the non-infected. 



(5) 



