268 THE INFECTIOUS DISEASES. 



any of the tissues, in the body cavities, and in the blood-vessels, it is 

 especially in the liver after death that the marks of gas accumulation 

 are most striking. This organ may be riddled with small holes, present- 

 ing an appearance which has been characterized as "foamy liver" (Fig. 

 371, page 608). 



Infection may occur through wounds or injuries in any part of the 

 "body. It has been frequently observed in pregnant and puerperal 

 women. Ulcers of the stomach and intestine, or the urinary tract, may 

 be portals of entry. One of the more common forms of local infection 

 is the so-called gaseous phlegmon or emphysematous gangrene. Pul- 

 monary and pleural lesions, appendicitis, and peritonitis are described 

 as well as gaseous abscesses and purulent meningitis. While the usual 

 action upon the tissues is the induction of bloody oedema and necrosis, 

 this bacillus is also occasionally pyogenic. 



The natural habitat of the organism is the soil and the intestinal canal. 

 This accounts for the relative frequency of infection through the intes- 

 tinal and genito-uriuary tracts and through wounds contaminated with 

 dirt. 



Infection, especially from the intestinal canal, may apparently occur 

 during the later hours of life, with or without symptoms and with a post- 

 mortem formation of gas. It is often difficult to determine, since gas 

 formation occurs so early and so extensively after death, whether the 

 entrance has or has not been effected during life. It seems fair to infer, 

 as the result of animal experiments, that when the gas formation, even 

 after death, is widespread, ante-mortem infection had occurred. 



Concurrent infection with other organisms, especially the pyogenic 

 cocci, is frequent. 



Welch and Nuttall early called attention to the importance of recog- 

 nizing the possibility of infection with this bacillus in judging of a cer- 

 tain class of cases of alleged air embolism. 



It is probable that the Bacillus aerogenes capsulatus is identical with 

 forms which have been described under various names in connection with 

 cases of gaseous phlegmon, or so-called malignant oedema. 1 



Bacillus CEdematis Maligni. 



The bacillus of malignant oedema, which is frequently present in dust, in putrefy- 

 ing substances, and in soil, considerably resembles the Bacillus aerogenes capsulatus both 

 in its morphological and biological characters. It is, however, more slender, and more 

 apt to form threads ; spore formation occurs readily in the ordinary media. It decol- 

 orizes partially by Gram's method. Other differential characters are to be made out in 

 cultures. It is an excitant of hsemorrhagic oedema in animals, but with slight if any 

 development of gas. 



Other Bacteria which May Induce Hsemorrhagic Septicaemia. 



Nearly related to the Bacillus aerogenes capsulatus and to the bacillus of malignant 

 oedema are several other spore- forming anaerobic bacilli occurring especially in the 

 earth, in excrement, and in various rotting substances. Some of these appear to be of 



1 For an excellent critical resume of this subject, with bibliography, see Welch, 

 Bulletin of the Johns Hopkins Hospital, vol. xi., p. 185, 1900. 



