^^6 History of Animal Plagues. 



grumous blood, as well as a lymphous fluid, show themselves frequently 

 in the substance. On the membranes of the cavities of the nose, and 

 the whole extent of the frontal finus, the large glands, and the medul- 

 lary substance of the horns, marks of inflammation and excoriation will 

 be seen. The kidneys and bladder are inflamed and void of urine. 

 The flesh in some beasts is livid, in others of a lively red for a short 

 time after the death of the beasts, but soon changing to a green colour. 

 Appearances are found of emphysema, or vesicles of air, in the lungs, 

 mesentery, and cutaneous membranes in various parts of the body. 



' From the whole of the symptoms and appearances of the murrain, 

 we may draw these conclusions as to the nature and effects of the dis- 

 ease : — It is communicated from one beast to another by a contagious 

 matter or virus, that, acting as a leaven, produces a ferment in the 

 humours of the parts into which it is introduced, and either reduces the 

 nerves of such parts to a paralytic or inactive state, or renders them too 

 irritable and active, at the same time counteracting those natural fer- 

 ments in such humours which are requisite for the due support of the 

 animal economy. But when, from the strength of the solids giving 

 due motion to the fluids, the natural ferments are duly powerful, it 

 cannot prevail over them, and therefore has no morbid effect, as we 

 see in those beasts which escape the infection, though exposed to the con- 

 tagion. In those subjects where there is a default of such strength, it 

 goes on by the above-specified means to weaken the force of the circu- 

 lation and deprave the secretions ; whence also that putrescence or putrid 

 ferment to which all animal substances have a natural tendency, when 

 not superseded by the vital ferments, is at length brought on, and if no 

 critical expulsion be made in due time of the contagious leaven by the 

 fever induced by its effects, destroys the vital economy, and necessarily 

 causes the death of the beast. But if, by the inflammation produced, 

 the force of circulation, and consequently the pov^^er of the vital ferment, 

 be so increased as to overcome that of the contagious leaven, the morbid 

 matter in which it resides is expelled, either in eruptions on the surface 

 or by a discharge from the intestines. 



' The progress and the manner of the action of the contagious virus 

 in the murrain may, from the symptoms and the appearances in the 

 dead beasts, be deduced to be as follows : — The first effects of the con- 

 tagion appear principally in the head and the upper parts. It produces 

 a certain degree of nervous weakness or paralytic disorder in those 

 parts, as is shown by the deafness, dulness of the eyes, debility of the 

 neck, and shaking of the head. This disorder aff"ects also gradually the 

 glands which secrete the saliva and lymph of the stomach, as there is 

 found, in a more advanced stage of this disease, a total want of those 



