360 DIPHTHEEIA 



oedema, and the lymphatic glands become enlarged, the general 

 picture resembling pretty closely that of laryngeal diphtheria. 

 The membrane produced by such experiments is usually less 

 firm than in human diphtheria, and the bacilli in the membrane 

 are less numerous. Rabbits inoculated after tracheotomy often 

 die, and Roux and Yersin were the first to observe that in some 

 cases paralysis may appear before death. 



Subcutaneous injection in guinea-pigs, of diphtheria bacilli in 

 a suitable dose, produces death within thirty-six hours. At the 

 site of inoculation there is usually a small patch of greyish 

 membrane, whilst in the tissues around there is extensive 

 inflammatory oedema, often associated with haemorrhages, and 

 there is also some swelling of the corresponding lymphatic glands. 

 The internal organs show general congestion, the suprarenal 

 capsules being especially reddened and often showing haemorrhage, 

 The renal epithelium may show cloudy swelling, and there is 

 often effusion into the pleural cavities. After injection the 

 bacilli increase in number for a few hours, but multiplication 

 soon ceases, and at the time of death they may be less numerous 

 than when injected. The bacilli remain practically local, 

 cultures made from the blood and internal organs giving usually 

 negative results, though sometimes a few colonies may be 

 obtained. If a non-fatal dose of a culture be injected, a local 

 necrosis of the skin and subcutaneous tissue may follow at the 

 site of inoculation. 



In rabbits, after subcutaneous inoculation, results of the same 

 nature follow, but these animals are less susceptible than guinea- 

 pigs, and the dose requires to be proportionately larger. Roux 

 and Yersin found that after intravenous injection the bacilli 

 rapidly disappeared from the blood, and when 1 c.c. of a broth 

 culture had been injected no trace of the organisms could be 

 detected by culture after twenty-four hours : nevertheless the 

 animals died with symptoms of general toxaemia, nephritis also 

 being often present (cf. Cholera, p. 408). The dog and sheep 

 are also susceptible to inoculation with virulent bacilli, but the 

 mouse and rat enjoy a high degree of immunity. 



Klein found that cats also were susceptible to inoculation. The 

 animals usually die after a few days, and post mortem there is well-marked 

 nephritis. He also found that after subcutaneous injection in cows, a 

 vesicular eruption appeared on the teats of the udder, tbe fluid in which 

 contained diphtheria bacilli. At the time of death the diphtheria bacilli 

 were still alive and virulent at the site of injection. The most striking 

 result of these experiments is that the diphtheria bacilli passed into the 

 circulation and were present in the eruption on the udder. He considers 

 that this may throw light on certain epidemics of diphtheria in which 



