CONTAGIOUS PLEUROPNEUMONIA. 369 



appeared in the State of New York was slaughtered early in 1891, 

 and the last one affected in New Jersey met the same fate early in 

 the spring of 1892. 



During these same years a supreme effort had been made to stamp 

 out this lung plague from Great Britain, From the official reports 

 it appears that the number of infected districts and of diseased ani- 

 mals had rapidly diminished, but it was not until 1898 that the in- 

 fection was finally eradicated. 



The other infected European countries, though they maintain a 

 veterinar}' sanitary service, are not making satisfactory progress in 

 eradicating the disease. This is owing partly to delays in carrying 

 out the provisions of the laws and partly to mistaken ideas as to the 

 measures which are necessary to accomplish the object. The United 

 States was the last of the countries having old infected districts 

 which undertook to stamp out this contagion, and, except Holland, 

 it Avas the first to reach success. 



The cause {etiology) of pleuropnewmoma. — This is a contagious 

 disease, and arises only by contagion from a previously affected 

 animal ; consequently it can never be seen here except as the result of 

 importing affected animals from the Old World. When thoroughly 

 stamped out it does* not reappear; and if imported animals continue 

 to be properly inspected and quarantined, we have every reason to 

 believe that pleuropneumonia will never again be seen in this 

 country. 



The exact nature of the virus or contagion of lung plague has 

 never been determined. Various investigators have from time to 

 time claimed the discovery of the specific organism of the disease, 

 but it was not until 1898 that Nocard and Roux, by an ingenious 

 method of cultivation, succeeded in obtaining a very feeble growth 

 of an exceedingly minute microorganism. With these cultures the 

 disease was produced in cattle. 



Some investigators and writers are of the opinion that the disease 

 can be contracted only by an animal coming near enough to a living 

 diseased one to receive the contagion directly from it. They hold 

 that the contagion is expired with the air from the affected lungs, 

 and that it must be almost immediately inspired by another animal 

 in order to produce the disease. Some experimental attempts to 

 infect animals by placing them in stables where diseased animals 

 have been, and by placing the diseased lungs of slaughtered animals 

 in their feeding troughs have failed, and, consequently, apparently 

 confirm this view. 



On the other hand, it is known that the serum from affected lungs 



retains its virulence and may be used successfully for inoculation 



weeks or months after the death of the animal from which it was 



taken. This is particularly the case when this liquid is hermetically 



54793°— 23 24. 



