402 BACILLUS AEROGENES CAPSULATUS. 



lation with living spores which have been deprived of adherent toxin by heat 

 does not produce the disease. 



The disease is one against which immunity can be readily produced in 

 various ways, and methods of preventive inoculation have been adopted in the 

 case of animals liable to suffer from it. This subject was specially worked out 

 by Arloing, Cornevin, and Thomas, and later by others. Immunity may be 

 produced by injection with a non-fatal dose of the virus {i.e. the cedematous 

 fluid found in the tissues of aifected animals and which contains the bacilli), 

 or by injection with larger quantities of the virus attenuated by heat, drying, 

 etc. It can be produced also by the products of the bacilli obtained by filtra- 

 tion of cultures. 



Bacillus aerogenes capsulatus. 



Bacillus aerogenes capsulatus (Welch). — Synonym : — Bacil- 

 lus Welchii (Migula). 



Introductory. — This organism was discovered by Welch in 

 1891 in the blood and tissues of a tuberculous person who died 

 from rupture of an aortic aneurism. The skin over the body 

 was markedly emphysematous, gas was found in the heart and 

 great vessels, in the loose tissues of the abdominal wall, and in 

 the various solid viscera, which presented the picture called by 

 the Germans, "Schaumorgane." A full description of the case 

 and of the bacillus was pubHshed by Welch and Nuttall the 

 following year. In 1893 E. Fraenkel pubHshed a monograph 

 on emphysematous gangrene and therein described an anaero- 

 bic bacillus as being the probable cause, naming it B. phleg- 

 mones emphysematosse, which, in all its details, morphological 

 and cultural, corresponded to that described previously by Welch 

 and Nuttall, and later acknowledged by Fraenkel as identical. 

 Since then this organism has been observed over and over again 

 by European workers, mainly ignorant of the American work 

 upon it, and given such names as B. perfringens, B. enteritidis 

 sporogenes, Granulo-bacillus immobilis, etc. In America in re- 

 cent years papers have appeared by Welch and Flexner, How- 

 ard, Bloodgood, Fulton and Pratt, and many others, recording 

 the occurrence of B. aerogenes capsulatus in the human body 

 under varied conditions. Welch, in 1900, reviewed the whole 

 literature and recorded many hitherto unpublished facts. 



Habitat. — The bacillus is widely distributed, being found 

 in the intestinal contents of most mammals, in sewage, in river 

 water, in garden and field earth, in dust, and in milk and many 

 raw foods. 



