ACUTE INFECTIOUS DISEASES. 



dence of contagious diseases on an infection of the body from low or- 

 ganisms be regarded as certain, the appearance of new infectious dis- 

 eases must seem a proof of the development of new species of organic 

 beings. Should not the varied malignity shown by epidemics of the 

 same disease at different times, and certain peculiarities of the indi- 

 vidual epidemics, be most simply referred to slight modifications, and 

 the gradual passage of certain phases of infectious disease in other 

 forms as extensive modifications of the low organisms ? 



The susceptibility to relapsing fever seems very general, and it 

 has often been noticed that almost every dweller in even large houses 

 exposed to the contagion was attacked by the disease. No age es- 

 capes the affection ; but most cases are among the young and middle- 

 aged. The predisposing influence of bad dwellings and insufficient 

 food is not to be mistaken. Poor people furnish so large a contin- 

 gent of the cases of relapsing fever that this cannot be explained solely 

 by their numerical preponderance over the well-to-do classes. Peo- 

 ple in good circumstances' have no immunity from this disease, and 

 nurses and physicians attending patients with it are not unfrequently 

 infected. One occurrence of relapsing fever does not seem to remove 

 the liability to it, as it does in other forms of typhus. 



ANATOMICAL APPEARANCES. The result of autopsies made in epi- 

 demics of febris recurrens of different intensity and malignity, together 

 with symptoms observed during life, justifies the following conclusions : 

 The infection of the organism by contagion not only induces high 

 fever running a peculiar course, but also pathological changes in vari- 

 ous organs, especially in the spleen, liver, and kidneys. Usually these 

 pathological changes consist only of disturbances of the circulation 

 and in such changes of structure as may be readily removed. But in 

 malignant epidemics more extensive structural changes develop in the 

 above organs, bearing partly the character of parenchymatous, partly 

 of suppurative inflammation. The disturbances of nutrition due to 

 relapsing fever have not a specific character, and do not differ from 

 those induced by other injurious influences. 



The corpses long retain a rigor mortis which occasionally begins 

 very early. The skin is usually light yellow, sometimes typically 

 jaundiced. At the dependent parts of the body there is extensive 

 postmortem hypostatic congestion. 



The muscles are not so dark as in other forms of typhus. On mi- 

 croscopical examination a more or less extensive degeneration of the 

 muscular fibrillae will be found ; they appear cloudy, indistinctly trans- 

 versely striated, filled with molecular fine granules, which disappear 

 on the addition of acetic acid, while the filaments become pale, and 

 show neither transverse nor longitudinal striae (l&Mtner). This degen 



