CHAPTEE XXV. 

 GROUP II. 



Acute infectious diseases caused by bacteria 

 which do not secrete strong soluble toxins in cul- 

 ture media, but which contain endotoxins (toxic 

 protoplasm). Infection or immunization causes 

 immunity of considerable or prolonged duration. 

 In active immunity the serums agglutinate the 

 corresponding organisms and are protective for 

 other animals 1 (anti-infectious), but have little or 

 no curative power. The formation of antitoxins 

 is not definitely established. In most instances 

 vaccination has been accomplished. Clinically 

 there is leucocytosis in some instances and hypo- 

 leucocytosis in others (typhoid and Malta fever). 



A. The serum in acquired immunity is increased 

 in bactericidal and opsonic power. 



I. TYPHOID FEVER. 



Eberth first saw Bacillus typhosus in micro- 

 scopic preparations of the mesenteric lymph glands 

 and spleen of a typhoid patient, in 1880. Koch 

 also observed it at about the same time, and 

 stained it in the intestinal wall, spleen, liver and 

 kidney. It was obtained in pure culture by Gaffky 

 in 1884. 



The organism is rod-shaped, 0.5 to 0.8. by from 

 1 to 3 microns in dimensions, with nothing char- 

 acteristic in its morphology. It possesses from ten 



1. This has not been established in regard to Malta fever. 



