PREVENTION OF PLEURO-PNEUMONIA. 189 



at remote periods, consistent with the process of incubation. If 

 it were otherwise, the inoculation, having been performed at one 

 time, should give rise to a contcm'pormuous appearance of the 

 iLsual symptoms, marked by a similar ciisis and decadence. 

 Experience, however, decidedly proves the reverse. 



The conv^eyance of the contagion of pleuro-pneumonia can be 

 readily referred to circumstances and events in which exposure 

 was permitted. About forty days has been found to elapse in 

 the majority of cases witnessed by the writer between the time 

 of infection and appearance of signs. In one notable instance, 

 an individual who was making experiments with diseased cattle 

 incautiously went direct from them to a fine herd of dairy cows, 

 some miles distant, in a clean, uninfected locality. At the 

 expiration of thirty-nine days one was taken ill, others followed 

 successively, and the whole were sacrificed. We have seen 

 certain infection to occur from the use of an uncleansed thermo- 

 meter, indiscriminately and intentionally used upon healthy 

 animals after being applied to the rectum of those already suffer- 

 ing. Such cases go to show the existence of the virus, and the 

 production of the essential disease by simple means, by which, 

 or doubtless some modification, the disease is generally con- 

 veyed. As yet we believe the true method of inoculation is not 

 known ; the simple fluid containing the necessary " virus," which 

 shall produce the exact disease, but in such a mild form as to 

 answer all the desirable ends, is still unobtained ; and, were it 

 even present with us, we have to confess w^e do not appreciate 

 its value. It is no part of our desire to underrate this operation. 

 We refrain from doing so because we recognise in the alarming 

 prevalence of pleuro-pneumonia throughout the British Isles, 

 and most of the countries of the European Continent, as well as 

 in South Africa and Australasia, at the present moment, as one 

 of the best and most conclusive pieces of evidence which can be 

 adduced of the inutility of the so-called inoculation. If the 

 alleged immunity from tlie disease is really obtained by inocula- 

 tion, and, as we have been informed, that hundreds, nay thou- 

 sands, of animals have been successfully operated upon ; also 

 that eighteen out of every twenty proprietors have tried it, and 

 regularly adopt it, how is it, we ask, that the disease is actually 

 increasing around us ? In the London dairies, as well as the 

 cow-houses of Manchester, Liverpool, Edinburgh, and Glasgow, 

 the process of inoculation may be seen almost any day. There 

 are also hundreds of animals to be observed with their tails 

 bandaged up, a piece of diseased lung tissue being strapped over 

 the wound ; and, notwithstanding this, the existence of the dis- 

 ease is denied, and even a defective system of inspection proves 

 its lamentable prevalence and spread from place to place. 



The absence of exanthema, or external eruption, as a natural 



