MILK SICKNESS, OR TREMBLES. 413 



Mississippi, and extends north to the boundary. The States of 

 Indiana and llHnois are most subject to its occurrence, whilst its 

 existence in the bordering Slates is comparatively rare. 



Its occurrence or prevalence is confined to no season, or description of 

 weather, existing in a like degree in the heat of summer or cold of win- 

 ter, and with like virulence and frequency during a dry or wet season. 



We will first speak of the symptoms manifested in cattle affected 

 with it, as it is only through them that we have yet found the disease 

 communicated to man. This may be affected to such a degree as 

 that their flesh and milk will produce the disease, and yet they them- 

 selves manifest no unhealthy symptoms whatever. This latent con- 

 dition of the disease may be discovered by subjecting the suspected 

 animal to n violent degree of exercise, when, according to the 

 intensity of the existing cause, it will be seized with tremors, spasms, 

 convulsions, or even death. This is a precaution practised by 

 butchers in these countries, always before slaughtering an animal in 

 anywise suspected of the poisonous contamination. An ordinary 

 degree of exertion will not develope these phenomena unless it pro- 

 duce the symptoms usually preceding a fatal termination. When, 

 for instance, a cow is sufficiently deeply aflfected, nothing peculiar is 

 observed until immediately preceding the outbreak of the fatal 

 symptoms. She is then observedto walk about, with out any appa- 

 rent object in view ; all food is refused, and there is evidence of 

 impaired vision. The eye is first of a fiery appearance, increasing to 

 a deep red color, until the animal is observed to stagger and fall, 

 when, if she rises, the trembling of the whole muscular system will 

 prevent the maintenance of the standing position. The animal usually 

 dies after repeated convulsions, never lingering beyond a few hours. 

 Often it falls suddenly, as if it received a blow from a heavy body on 

 the head, and death is produced in a few minutes. 



The cause of this disease of animals is as yet shrouded in mystery 

 and uncertainty. No satisfactory account of its nature has yet been 

 given, and it has in turn been supposed to be of vegetable, mineral, 

 and even aerial origin. The limits of its prevalence is not often over 

 a large and continuous tract of country, but rather circumscribed, 

 and surrounded by localities never known to produce it. No exam- 

 ple^ is known in which the property of producing the disease has been 

 acquired by any locality which did not previously possess it. The 

 boundaries which were at the first discovery of the country found to 

 separate the infected from the healthy districts, remain unchanged. 

 The locality which serves to produce the disease, most commonly 

 extends as a vein of variable breadth, traversing the country for a 

 considerable distance. It can be traced in one instance fi»r nearly a 

 hundred miles, running parallel to the course of the Wabash river, in 

 the State of Indiana, 



Again, it will be found to occupy an isolated spo: comprised in 



