1890.] A Contribution to the Etiology of Diphtheria. 73 



patients amongst cats affected with the disease, consisting in an 

 acnte catarvhal affection, chiefly of the respiratory passages. Ho 

 furnished me with two such animals : one that after an illness of 

 several weeks had died, another that was sent to me in a highly 

 emaciated state, affected with severe broncho-pneumonia; this animal 

 was paralysed on the hind limbs. In both instances the post-mortem 

 examination showed severe lung disease, broncho-pneumonia, and 

 large white kidneys due to fatty degeneration of the entire cortex. 

 A similar condition is met with in the human subject in diphtheria. 

 Further, I received from Dr. Thursh'eld, of Shrewsbury, the body of 

 a cat that had died after a few days' illness from pneumonia in a 

 house in which children were ill with diphtheria ; another cat ki the 

 same house that became next ill with the same lung trouble also 

 succumbed. The post-mortem examination of the animal that I 

 received showed severe broncho-pneumonia and large white kidneys, 

 the entire cortex being in a state of fatty degeneration. 



Subcutaneous inoculations of cats were carried out with particles of 

 fresh human diphtheritic membranes and with cultures of the 

 diphtheria bacillus (' Report of the Medical Officer of the Local 

 Government Board,' 18891890) ; hereby a local diphtheritic tumour 

 was produced at the seat of inoculation, and a general visceral disease ; 

 in the cases in which death followed after a few days the lungs wero 

 found much congested; when death followed after one or more weeks, 

 the lungs showed broncho-pneumonia and the kidneys were enlarged 

 and white, the cortex being in a state of fatty degeneration ; if the 

 disease in the animals lasted beyond five to seven days, both kidneys 

 were found uniformly white in the cortex ; if of shorter duration, the 

 fatty degenei*ation was sometimes only in patches. Although in 

 these experiments the bacillus diphtherias was recoverable by cultiva- 

 tion from the diphtheritic tumour at the seat of inoculation, there 

 were no bacilli found in the lungs, heart's blood, or kidney, and the 

 conclusion is justified that, just as in the human diphtheria and in the 

 diphtheria produced by subcutaneous inoculation in the guinea-pig, 

 so also in these experimental cats the visceral disease must be a 

 result of the action of a chemical poison produced by the diphtheria 

 bacillus at the seat of inoculation. 



From this it is seen that the similarity between the artificial disease 

 and the natural disease in the cat is very great, and the question that 

 presents itself is, In what manner does the animal receive or give the 

 diphtheritic contagium in the natural disease ? The natural disease in 

 the cat is in its symptoms and pathology a lung disease, and it is 

 reasonable to suppose from analogy that the lung is the organ in 

 which the diphtheritic process in the cat has its seat. The micro- 

 scopic examination of the diseased lung of cats that died from the 

 natural disease bears this out, the membrane lining the bronchi in the 



