THE LUNG PLAGUE OF CATTLE. 49 



M 



N AIUKE OF LUNG PLAGUE. 



Tliaf tin* lung plague is determined by an infect ing material conveyed 

 t'roni beast to beast is without doubt. The presence of such a specific 

 contagion is demonstrated in all experience of the disease and its pro- 

 pagation, and in the value of inoculation as a protect ing measure. The 

 intimate nature of that contagion may now be held as all but proved by 

 the investigations of Professors Bruylauts and Verriest of the Univer- 

 sity of Lou vain. 



As early as KS"^, Willems and Van Kempen, of Ilasselt, Belgium, re- 

 corded the presence in the lymph of the diseased lung, of myriads of 

 peculiar corpuscles which were absent from the juices pressed from a 

 healthy lung. Others at different times confirmed these observations as 

 to the presence of the corpuscles, but their action as factors in the cau- 

 sation of lung plague remained unproved. 



In the course of the past year Bruylants and Verriest in a long series 

 of experiments found the organisms in question in the liquids of the 

 freshly diseased lungs, and in that of the local swellings resulting from 

 inoculation, but not in the blood nor textures of tlie body generally, and 

 not always in the liquids effused into the chest. They have cultivated 

 this germ through a succession of generations in glass flasks, and found 

 that at any time it continued to prove infecting to susceptible bovine 

 animals, and that it retained its virulent qualities after it had been pre- 

 served fora month in a hermetically sealed glass tube. Cultures made 

 with fresh portions of healthy lungs and those made with small parti- 

 cles of other tissues led to no milkiness nor other change from the growth 

 of micrococci in the organic liquids, and produced no specific inflamma- 

 tion in wounds when inoculated. Finally a moist heat of 60 Cent. 

 (140 Fah.) for fifteen minutes invariably proved fatal to the germ, so 

 that this may be held to be the limit of its viability, and boiling water 

 or colorless steam may be accepted as an efficient disinfectant. 



In the light of these experiments, it seems that the lung plague is a 

 true bacteridian disease, like malignant anthrax and swine plague, the 

 seat of the malady being determined by the point at which the micro- 

 coccus gains access to the system. Thus inspired, as it usually is, with 

 the air, it finds its way through some slight abrasion of the pulmonary 

 mucous membrane, or through the delicate lining of the air cells or mu- 

 ciparous follicles into the submucous connective tissue, where it propa- 

 gates itself abundantly, destroys the integrity of the lymphatic radicles, 

 and leads to the extensive inflammation and exudation. Inoculated on 

 some superficial part, where there is a great abundance of connective 

 tissue, as the dewlap or shoulder or root of the ear, it leads to a similar 

 extensive inflammation and exudation, followed usually by death. But 

 if inoculated on the tip of the tail, where connective tissue is scanty and 

 the lymphatic system is but poorly developed, it gives rise to a small 

 and harmless swelling, usually not exceeding the size of a heii's egg. 



The morbid processes are mainly confined to the connective tissue and 

 lymphatic system, and there is some reason to suppose that the micro- 

 coccus can live with difficulty, if at all, in the living.blood. This may be 

 inferred from the fact that the disease does not attack the natural seat 

 of its invasion the lungs when it has been inoculated on the tail, nor 

 does it affect any distant part of the body when it has occurred natu- 

 rally in the lungs. Add to this that Bruylants and Verriest failed to de- 

 velop the micrococci with certainty from the blood, or from any other 

 part of the body than the diseased lung, and that Burdon- Sanderson 

 S. Ex. 106 4 



