1907.] on Certain Seasonal Diseases of the Sheep. 537 



of last year. It gave an account of the work, so far as it had gone 

 up to the date of pubHcation. (" Report on the two Diseases of the 

 Sheep, known as Braxy and Louping-ill." Board of Agriculture and 

 Fisheries, 1906.) 



Diseases in question form a Group. — The sheep is peculiar in 

 respect of the many contagious diseases to which it is liable, and it is 

 curious that heretofore they have not claimed more attention than 

 has been awarded to them.' Those with which we are more imme- 

 diately concerned form a large group, the members of which are 

 closely related, in so far as they are each caused by a specific 

 organism having certain mutual affinities, and, apparently, of the 

 same type as that of Tetanus. Several of the group have never, 

 up till now, been recognised, and those whose characteristics have 

 claimed attention have been investigated only in a perfunctory 

 manner. Previous to the work of the Board of Agriculture Com- 

 mittee, little was known of most of them which could serve to ex- 

 plain their pathology and aetiology, or lead to their prevention. 



So far as my own observations have demonstrated, the members 

 of the group are comprised in the following : — Braxy {Morbus suhi- 

 tarius oris), Louping-ill or Trembling {Chorea paraJytica ovis), 

 Malignant (Edema of the sheep, Blackquarter or Quarter Evil, the 

 disease known as " Struck," and two diseases which, provisionally, I 

 have named Disease " A " and Disease " B." 



Each (hie to an Anaerobic Bacillus. — Some of them, such as Braxy, 

 appear to be peculiar 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 goat, but only on rare occasions. Each of 

 them is caused by an anaerobic bacillus, having a great tendency to 

 spore, and whose natural habitat is the intestine. 



Their Periodicity. — One remarkable feature of these diseases of 

 the sheep 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 Mahgnant 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 Avest 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. 



Braxy is a most destructive disease in Iceland, the Faroes, and 

 the Avest 'coast of Norway ; in fact, it may be asserted that wherever 



