180 PREVENTION AND TREATMENT OF SCABIES. 



Secondly, the grease with which the mercury is incor- 

 porated in preparing the ointment, tends to mat together the 

 long fleeces of the Lincoln sheep. If the wool is opened out 

 a few days after salving, it will be found knotted and 

 plastered together so as to form an effectual and impervious 

 covering, condensing the perspiration on the surface of the 

 skin, and, indeed, soon arresting the action of the skin alto- 

 gether. This cause operates most potently in inducing a 

 poisoned condition of the blood, and is, in my opinion, the 

 direct cause of the apnoea or suffocation, the pulmonary 

 congestion and suffering characteristic of the "supposed lung 

 complaint in sheep/' 



Physiologists have long since shown that covering the skin 

 with an impermeable coa.ting is destructive to the life of an 

 animal. Fourcault, Magendie, and others have observed 

 that if any quadruped has its skin covered with an imper- 

 meable varnish, or if the body is covered closely by a 

 Mackintosh, leaving the head alone exposed, death soon 

 occurs from suffocation. I have drawn attention in Scotland 

 to the fatal results of covering lambs, especially when in a 

 plethoric state, with the skin of the natural offspring of a 

 ewe. Many more would die from this cause if the skins 

 were kept longer on ; but in any flock with a tendency to 

 blood-disease, the lambs die in a few hours, with their lungs 

 gorged and frothy mucus in the air-passages. These results 

 are due to the accumulation in the blood of carbonic acid, 

 ammonia, and organic products, which should be constantly 

 thrown off by the skin. It is very important that I should 

 notice the influence of the dry weather in producing the dis- 

 order. Had there been much rain the fleeces would have 

 opened up and been moist, whereas the dust and dirt have 

 materially contributed to consolidate the matting which has 

 so effectually checked the skin's exhalations. 



