Lung Plague in Cattle. 669 



monary exudate which had just been heated for 30 minutes to 

 180'' F. No local inflammation nor exudate occurred in any of 

 them, but subsequent inoculations with fresh unsterilized lung 

 plague exudate were resisted in the same way. Six of these im- 

 munized cattle were subsequentl}^ placed in two infected stables 

 and herds, (Mr. Butts, Brooklyn, N. Y., and Mr. Christopher 

 Slade, White Hall, Baltimore Co., Md.) and retained there for 

 three months without showing the slightest indication of disease. 

 I^ater I applied the measure on a number of herds with throughly 

 satisfactory results. About ten years later a similar resort was 

 had by Arloing and Rossignol with corresponding success. 



Two advantages come from this method : ist, there is no local 

 infection and no marked swelling so that the injection can be 

 made on the side of the neck where the skin is thin, and clean, 

 and the connective tissue abundant, and where there is less risk 

 • of extraneous infection than in the too often dirty or filth soaked 

 tail ; 2nd, as no living germ is introduced there is no possibility of 

 propagating the disease to other neighboring susceptible animals. 

 Two per cent, of loss, of animals inoculated by the Willem's 

 method is counted on, but with the sterilized virus there is not 

 even a remote probability of loss. Infection cannot occur from 

 the animal injected with the sterilized virus, so that it can be 

 safely applied among cattle that have not been exposed to infec- 

 tion, but which are likely to be in the future, and these injected 

 cattle can be left to mingle with others that have not been in- 

 jected without a shadow of danger to either. 



Conditions permitting and forbidding Immunization. Im- 

 munizaton is permissible or commendable in all cases in which 

 lung plague is already widely spread in a land destitute of fences 

 and in which cattle roam at large, and herd mingles freely with 

 herd. Here the extension of the disease is inevitable and con- 

 tinuous and effective measures for extinction are impossible. It is 

 permissible where the plague is widely spread among cultivated 

 and fenced farms, but where no authoritative measures are in 

 force for its extinction. In such case, with the Willem's system 

 the inoculated herd should be kept thoroughly secluded in 

 premises or well fenced pastures, apart from any highway, and 

 not adjoining any other cattle pasture. 



When on the other hand oflScial measures are in force for the 

 extinction of lung plague, every form of immunization based on 



