140 CONTAGIOUS DISEASES. 



the poison of the disease, so that serum obtained from it will 

 give the disease by inoculation. This fact was ascertained by 

 Dr. Sanderson, and is a most important discovery, and, accord- 

 ing to the Commissioners, "is pregnant with consequences in 

 medical doctrine ; " for though (they say) the existence of a 

 similar fact has long been suspected in several human diseases, 

 it has never been proved in any. When the Commissioners 

 made this assertion they were evidently ignorant of the 

 fact that Coleman had demonstrated the presence of the 

 glanders poison in the blood, and had induced glanders by 

 transfusion. 



The morbid poison is also contained in the discharges from 

 the mouth, eyes, intestinal canal, &c. of an animal ill from the 

 cattle plague, and a small quantity of the mucus from the nose, 

 eyes, or mouth, when placed in the blood of a healthy animal, 

 increases so fast, that in less than forty-eight hours, perhaps in 

 a shorter time, the whole mass of blood, weighing many pounds, 

 is infected, and a very small particle of that blood contains 

 enough poison to give the disease to another animal. This at 

 once accounts for the rapid spread of the cattle plague. The 

 microbe is multiplied to a large amount in a very short space 

 of time. How soon after it is put into the blood the animal 

 becomes capable of giving the disease by natural infection 

 to other animals is not determined, but in all probability 

 long before it is, as it were, impregnated with the poison ; 

 for it stands to reason that all parts of the body, out of 

 which secretions are poured, must contain more or less morbific 

 material when that material is contained in the whole mass 

 of blood. 



It has not been determined to what length of time the blood 

 and textures retain the power of propagating the disease. Pro- 

 fessor Jessen of Dorpat, however, says that the mucous discharges, 

 carefully protected, occasionally retain their power of causing the 

 disease by inoculation for no less than eleven months. 



The virus, which is both volatile and fixed, can be diffused and 

 the disease communicated by the air for a distance of about five 

 hundred yards ; but beyond this distance it remains inoperative. 

 It is also conveyed by flies, which, after resting on a sick animal, 

 or its offal, fly about and alight on healthy animals ; and by the 

 offal of animals dead of the disease ; by hay, bedding, dung, 



