366 DISEASES or the sheep. 



eased ^ but it is only when the fluids are altered, and some- 

 times essentially changed, and the condition of the digestive 

 organs is materially impaired, that their appearance is fa- 

 vored, or their multiplication encouraged. 



WHAT, THEN, IS THE CAUSE OF THE EOT IN SHEEP 1 



The knowledge of the cause can alone guide us to a 

 cure, or at best to the prevention of it. It does not arise 

 from deficiency of food ; a sheep may be reduced to the 

 lowest state of condition — he may be starved outright, but 

 the liver would not be necessarily as often in a diseased 

 state. It is not to be traced to the effects of sudden flush of 

 grass. The determination of blood to the head, diarrhoea, 

 dysentery, might be thus produced, but not one symptom re- 

 sembling rot. Some persons, led away by a favorite theory, 

 have traced it to defective ventilation ; but in the closest 

 keeping to which the British sheep is usually committed 

 there is no foul air to be got rid of, and defective ventilation 

 would be words without meaning. * # * # 



The rot in sheep is evidently connected with the soil or 

 state of the pasture. It is confined to wet seasons, or 

 to the feeding on ground moist and marshy at all seasons. 

 It has reference to the evaporation of water, and to the pres- 

 ence and decomposition of moist vegetable matter. It is 

 rarely or almost never seen on dry or sandy soils and in 

 dry seasons. In the same farm there are certain fields on 

 which no sheep can be turned with impunity. There are 

 others that seldom or never give the rot. * * * 



Some seasons are far more favorable to the development 

 of the rot than others, and there is no manner of doubt as 

 to the character of the seasons. After a rainy summer, or 

 a moist autumn, or during a wet winter, the rot destroys like 

 a pestilence. A return and a continuance of dry weather 

 materially arrests its murderous progress. It is, therefore, 

 sufficiently plain that the rot depends upon, or is caused by 

 the existence of moisture. A rainy season, and a tenacious 

 soil, are fruitful or inevitable sources of it. 



But there is something more than moisture necessary for 

 the production of rot. The ground must be wet, and its 

 surface exposed to the air ; and then the plants-, previously 

 weakened or destroyed by the moisture, will be deconlposed ; 

 and, in that decomposition, certain gases or miasmata will 



