TYPHOID BACILLI IN MILK. 297 



Stab Cultures. — In stab cultures the growth is 

 mostly on the surface, there being only a very limited 

 development down the track made by the needle. The 

 surfacij growth has the same appearance in general as 

 that given for the colonies. 



Potato. — The growth on potato is usually described 

 as luxuriant but invisible, making its presence evident 

 only by the production of a slight increase of moisture 

 at the inoculated point, and by a limited resistance 

 offered to the needle when scraped across the track 

 of ^owth. While this is true in most cases, yet it 

 cannot be considered as constant, for at times this 

 organism is seen to develop more or less visibly on 

 potato. 



Potato Gelatin. — The growth is similar to that 

 upon ordinary nutrient gelatin. 



Milk. — It does not cause coagulation when grown in 

 sterilized milk. 



It does not liquefy gelatin. 



It grows both with and without oxygen. 



It does not produce indol. 



In bouillon it causes a uniform clouding of the 

 medium and brings about a slightly acid reaction. 



It does not grow rapidly. 



It does not produce fermentation, and on lactose- 

 litmus-agar grows as pale-blue colonies, causing no 

 reddening of the surrounding medium. In the fermen- 

 tation tube, in glucose or lactose bouillon, no evolution 

 of gas as a result of fermentation occurs. 



It does not form spores. The irregularities of stain- 

 ing so commonly seen in this organism have in some 

 instances led to the belief that the pale, unstained por- 

 tions of the bacilli indicate the presence of spores. 



