AN AEROBIC SPORE-FORMING BACILLUS 11 



tory, working independently. The tests were run as follows: 

 tubes of standard lactose broth, with inverted vials, were placed 

 in a water-bath, brought to the desired temperature and regu- 

 lated to within 1°C. After the tubes had attained the tempera- 

 ture of the water-bath, 0.1 cc. of a light suspension of the organ- 

 ism taken from the surface of a seventy-two hour old agar slant 

 was carefully added to the tube and the time noted. At suitable 

 intervals, two tubes were withdrawn and put into cold water to 

 cool. After seventy-two hours' incubation at 37°C. the tubes 

 were examined and the growth and gas production recorded. 

 Where there was no gas production the tubes were sterile. Agar 

 slant cultures made from the broth tubes showing gas revealed 

 the spore-former in pure culture. 



MORPHOLOGY AND STAINING CHARACTERISTICS 



In smear preparations made from, forty-eight hour old agar 

 slants three distinct forms, representing different stages of the 

 bacillus, are seen. First there is the vegetative cell, a regular 

 rod with rounded ends. Gram negative, 4.5 to 5.5 by 0.8 to 1 /x 

 Next is the spore-bearer, spindle-shaped. Gram-negative, about 

 3 by 1.5 fx. With ordinary stains the spore is shown as a 

 central, oval, unstained area, and with Mtiller's spore stain is 

 readily demonstrated. The third form is the free spore, oval, 

 regular, 2 by 1.5 /x, showing deep red with the spore stain. 

 These occur most frequently and regularly in older cultures. 



No capsules could be demonstrated by the use of the Welch 

 capsule stain in smear preparations from milk cultures. When 

 stained -by Loffler's method, the organisms show numerous peri- 

 trichic flagella, some bacilli showing as many as 16 to 18. Not- 

 withstanding this fact, motility has not been observed when 

 using the hanging drop method. 



APPEARANCE AND REACTIONS IN VARIOUS MEDIA 



Agar slant. Growth quite distinctive. At 37°C., in twenty- 

 four hours, thin transparent veil-like growth over entire surface 

 except the very top. Growth lobate along upper edge. Micro- 



