Bacillary Dysentery 701 



mitted light they appear granular and of a yellowish color. 

 They do not spread out in a thin pellicle like those of the 

 colon bacillus, and there are no essential differences between 

 superficial and deep colonies. 



Gelatin Punctures. The growth in the puncture culture 

 consists of crowded, rounded colonies along the puncture. 

 A grayish- white growth forms upon the surface. There is 

 no liquefaction of the gelatin. 



Agar-agar. Upon the surface of agar-agar, cultures 

 kept in the incubating oven show large solitary colonies at 

 the end of twenty-four hours. They are bluish- white in 

 color and rounded in form. The surface appears moist. 

 In the course of forty-eight hours a transparent border is 

 observed about each colony, and the bacilli of which it is 

 composed cease to stain evenly, presenting involution forms. 



Glycerin agar-agar seems less well adapted to their growth 

 than plain agar-agar. Blood-serum is not a suitable medium. 



Litmus Milk. Milk is not coagulated. As the growth 

 progresses there is slight primary acidity, which later gives 

 place to an increasing alkalinity. 



Potato. Upon boiled potato the young growth resembles 

 that of the typhoid bacillus, but after twenty-four hours it 

 becomes yellowish brown, and at the end of a week forms 

 a thick, brownish-pink pellicle. 



Bouillon. In bouillon the bacillus grows well, clouding 

 the liquid. No pellicle forms on the surface. 



Metabolic Products. The organism does not form in- 

 dol, does not ferment dextrose, lactose, saccharose, or other 

 carbohydrates. Acids are produced in moderate quantities 

 after twenty-four hours. Milk is not coagulated. Gelatin 

 is not liquefied. 



Toxins, chiefly endotoxins, are produced. They may best 

 be prepared by making massive agar-agar cultures in Kitasato 

 flasks or flat-sided bottles, and after growth is complete 

 washing off the bacillary mass with a very small quantity of 

 sterile salt solution, and after killing the bacilli by exposure 

 to 60 C. for fifteen to thirty minutes, permitting the rich 

 suspension to autolyze for three days. The toxins may be 

 precipitated from the sodium chlorid solution by ammonium 

 sulphate. 



Vital Resistance. The thermal death-point is 68 C. 

 maintained for twenty minutes. It grows slowly at ordi- 

 nary temperatures, rapidly at the temperature of the body. 



