Me fayden reaction seen with which organism -

Ans. is 'd' i.e., Bacillus antracis M' FadyeaiTs reaction* When blood films containing anthrax bacilli are stained with polychrome methylene blue for a few seconds and examined under microscope, an amorphous purplish material is noticed around bacilli. This represents the capsular material and is characteristic of the anthrax bacillus.