PATHOGENIC MICROORGANISMS. 185 



Chicken Cholera. 



By whom was the Bacillus cholerse gallinarum discovered, and by whom 

 described ? 



Describe this bacillus. 



How does it stain ? 



Give its principal biologic characters. 



What is the appearance of the cultures on gelatin to the naked eye? How 

 do they look when seen under the microscope? 



What animals are subject to infection ? Which animals are immune? 



What sort of infection is produced in animals by the inoculation of this 

 bacillus ? 



What is effected by feeding animals with material contaminated with this 

 bacillus ? 



How are protective inoculations performed? 



To what extent is this bacillus pathogenic to rabbits? 



Under what different names has this bacillus been described by various 

 authors ? 



CHAPTER XXIII. 



THE PATHOGENIC MICROORGANISMS OTHER THAN 

 BACTERIA. 



ACTINOMYCOSIS, MALARIA, AND AMCEBIC COLITIS. 



Streptothrix. 



THE streptothrix group, which has not as yet been clearly 

 defined, presents a number of varieties which have been 

 found pathogenic. This group of microorganisms resembles 

 the bacteria, yet differ from them in a number of important 

 respects, and are associated, on the other hand, with the 

 moulds. They resemble the moulds in so far that they develop 

 from spore-like bodies into dichotomously branching threads, 

 which grow into colonies having more or less the appearance 

 of true mycelia. Under favorable conditions some of the 

 threads become fruit hyphae and break up into a number of 

 spore-like bodies. These sporiform bodies differ from bac- 

 terial spores in the fact that they are stained by the ordinary 

 method of staining. They resemble the bacteria in the fact 



