History of Animal Plagues. 379 



'On one side^ it is said, a virus of a caustic, acrid, and in- 

 flammatory nature, received into the air and digestive passages, 

 corrupts the juices and infects the chyle; this milky liquid, 

 carried into the mass of the blood, can only reach it by passing 

 through the principal channels which nature has destined for 

 the lymph ; these necessarily contract the taint, from whence 

 the engorgement of the vessels which contain it, as well as the 

 conglomerate glands, Sec. If this virus is of a character to become 

 thickened and consolidated, the engorgement augments, the 

 lymph becomes depraved by its ceasing to flow, and irritates 

 and inflames the tunics; when carried in this state into the 

 mass of the blood it corrupts it; and from this arises the general 

 depravation of the humours, and the swelling of the glands; a 

 symptom which always indicates that the mass of the humours 

 has received the leaven of contagion. If the action of the virus 

 is limited to the digestive tract, it produces difierent symptoms 

 throughout the whole of the intestinal canal, such as colic, spas- 

 modic tensions, a contraction in the mouths of the lacteal ves- 

 sels, diarrhoea, dysentery, &c., symptoms which are oftentimes 

 observed at the commencement of the disease; and dead bodies 

 have been opened in which all these viscera, with the excep- 

 tion of the third division of the stomach, have been found 

 healthy; in this part the poison appeared to have concentrated 

 its effects. In other subjects, no sensible alteration was found save 

 excessive distension of the gall-bladder. But this often sufficed to 

 produce death ; a circumstance which proves the malignity and 

 the subtilty of the contagious ferment, which was capable of de- 

 stroving vitality, even before it perceptibly infected the humours. 

 All observers agreed that its deleterious action on the nerves, 

 and on their oritiin, was the first and the most danirerous effect 

 it produced in the animal economy; it is that which is always 

 the characteristic of the most dreaded diseases of men and 

 animals, and which often decides their nature, 



' On the other side, according to Boerhaave^s theory of in- 

 flammation, it was admitted that the indirect as well as im- 

 mediate cause of the disease was the arrest and stagnation ot 

 the blood In tiit: extreme cai)illaries of tiie vessels, followed by 

 sudden inflannnation and rapid gangrene. 'I'lie Ijjood engorging 



