i38 



LOUPING-ILL AND BRAXY, 



[JUNE, 



- Those sheep which, vvhen grazing, pick up the organism during 

 the season when they are not susceptible (viz., when the blood 

 can destroy it) usually allow of its passage along the intestine 

 without detriment, and are evidently thus rendered immune, so 

 that when the period of danger arrives they fail to take the 

 disease. 



On the other hand, sheep which pick up the organism for the 

 first time during the dangerous period (viz., when the bacillus 

 can grow upon the blood), have little power in resisting the 

 passage of the organism into the peritoneal cavity, and, conse- 

 quently, many of them fall victims to the disease. 



This theory accounts (i) for the larger death-rate among 

 lambs and hoggs, (2) for the excessive mortality which occurs 

 when sheep are brought from " clean " on to " foul " ground 

 during the spring months. 



z It may be mentioned that there is no evidence to show that 

 louping-ill is infectious in the sense of a fever. Very few, if 

 any, sheep take it a second time ; it is doubtful whether those 

 which apparently do so have not previously suffered from some 

 other complaint having symptoms more or less resembling those 

 of louping-ill. 



Braxy and Allied Diseases. — It had previously been suspected 

 tliat various diseases passed under the name of braxy, and this 

 proved not only to be the case, but, further, it was discovered 

 that louping-ill, braxy, and several other diseases as yet only 

 partially examined, form a most interesting and important 

 group, closely allied, all acquired through the fodder, all caused 

 by anaerobic bacteria, whose habitat is in the alimentary canal,, 

 and all of which are subject to the peculiar seasonal action of 

 the blood described above under louping-ill. Referring to the 

 group the report (Part II., p. 329) says : "The side issues that 

 have cropped up show how little the diseases to which sheep are 

 Itable- are understood — -how much, in fact, they are misunder- 

 stood — and what necessity there is for more extended and 

 trustworthy knowledge of their nature and cause. From a 

 pathological point of view, they are a perfect mine of wealth^ 

 are fraught with scientific problems of the highest interest 

 and importance, and are most suggestive of what may turn 

 out to be a new light on the pathology of many of the. 



