History of A uimal Plagties. 311 



relating to it in a clear and decisive light. There are some opinions 

 respecting it, in which all agree, because they are supported by evident 

 instances ; but there are others which, though they have the sanction 

 of common assent, may yet be disputed on very just grounds. It is 

 unquestionably certain, that the murrain is communicated by transmis- 

 sion of some contagious matter from beasts which have that disease to 

 those which are sound 3 but that this is done by all the means of com- 

 munication generally supposed is not at present so manifest a matter. 



* The effect of inoculation in the murrain, as well as a great number 

 of other palpable facts, render it plain that the contagious matter 

 may be carried by other bodies, which receive it from the diseased 

 beast, and convey it, by actual contact, to the sound. This may be 

 performed by any substance to which the infecting particles can adhere, 

 but is most likely to happen, through accident, by the mediation of any 

 body that is of a hairy, woolly, or pilous texture,' because the matter is 

 much less liable to be rubbed or cleansed off" from such bodies, than from 

 those which are denser and have an entire and smooth surface. 



'But there is another mode of conveyance of the infection, which, 

 though it must be allowed to subsist with regard to some contagious dis- 

 orders, admits of a doubt with respect to the murrain, that is, the com- 

 munication of the contagion by the air. It is in general taken for 

 granted that the air is the chief vehicle of the contagion of this disease, 

 and several means of prevention of its action have been instituted on 

 that principle. But there is no clear fact which in the least proves this 

 notion, and the universal failure of the preventive means founded on it, 

 furnishes arguments against it, as far as anything at all can be thence 

 inferred. On the other hand, a great number of circumstances seem to 

 evince that the cattle are never infected but by an actual conveyance 

 of the contagious matter, by means of contact of a sound beast with one 

 that is diseased, or with some other body, which receives first the viru- 



^ It has, however, been strangely made a matter of doubt by some eminent 

 professors in the United Provinces, whether the skin itself of a dead infected beast 

 would impart the contagion, and they have even asserted the negative, in con- 

 sequence of the result of certain experiments made for the determination of this 

 point. But some fallacious circumstance attended those experiments, as appears 

 even on the face of the relation. It would, indeed, require very strong proofs to 

 gain assent to such an opinion, than which a stranger paradox can scarcely be 

 advanced. It is evident the infection is conveyed by other substances ; and nothing 

 can be more suited to collect and retain the matter of it than a hairy skin. The 

 matter must, undoubtedly, abound in the skin of the beast which generates it, 

 whether it be evacuated by tiie perspiration, saliva, or any other excretion. Indeed, 

 whatever other bodies convey it must in general receive it from the skin, which, 

 if it can impart the same to them while the animal is living, must, in common withi 

 oilier bodies, retain it a certain time after the beast is dead. 



